A fire inside the massive ExxonMobil refinery cast an orange glow across the Baton Rouge sky early Wednesday, alarming residents but causing no injuries and no major impact on production at the sprawling industrial facility, company and state officials said.

The blaze broke out late Tuesday, just before midnight, and ExxonMobil's volunteer fire team extinguished the fire by 7 a.m. State and company officials said there was no evidence the fire or its fallout were a risk to residents.

"The whole sky lit up, bright enough to be daytime," said Denny Butler of Zachary, who was driving home to Zachary along Interstate 110 when he noticed the flames. He drove to the plant, thinking of friends who work there and hoping they were OK. 

ExxonMobil officials said the fire was isolated to the area where it began and that there appeared to be no danger offsite.

The refinery is the company's second largest in the U.S., behind only one at Baytown, Texas. The company is a major employer in the region, at its refinery and also at its chemical, polyolefins and resins plants. Combined, Baton Rouge's ExxonMobil facilities had about 7,000 workers in 2018, including contractors. More than 3,000 worked in the refinery as an employee or contractor, according to the company.

While some near the plant said they believed they had heard an explosion, company officials and Baton Rouge Fire Department spokesman Curt Monte said none had occurred. Several who live nearby slept through the tumult and learned about the blaze when they woke up.

"That was news to me when my granddaughter called on her way to work and asked if I was alright," said Martha Robertson, 82, who's lived in the shadow of the Exxon refinery for the past 50 years and has no plans of moving. "I said, 'What! What do you mean?' and then I saw it on the news."

The company started offering buyouts to people living closest to the plant decades ago following a 1989 blast that killed two workers and damaged buildings miles away. All but a few homeowners have accepted such offers since then. But not Robertson.

The Baton Rouge great-grandmother said she's never been particularly worried about her safety living so close to the plant — even after all her windows shattered in 1989 — although the chemical smell bothers her during rainy weather when the air feels heavy. She would have taken a buyout years ago but said the offer wasn't enough to support her moving her entire family, especially after her husband's unexpected death left her to raise four children as a single parent. 

"I guess it must be getting dangerous now, maybe I should be worried," she said with a wry smile Wednesday morning. "We would be the first to go if anything really did happen. … But I'm not going anywhere. I can't start all over again."

The cause of the fire wasn't known Wednesday. ExxonMobil said it would launch its investigation once workers could safely enter the area. Sources familiar with the refinery's operations said the fire started in a natural gas pipeline that supplied the crude distillation units.

Officials said the fire, which reached well beyond 50 feet into the air, likely burned most of any chemicals involved. 

"ExxonMobil will continue to actively monitor the facility fence line and air quality in the surrounding areas of the North Baton Rouge community," company spokesman Danny Lee said, adding that "all readings are non-detect." The Baton Rouge Fire Department reported the same results.

Greg Langley, a state Department of Environmental Quality spokesman, said his agency is investigating the fire, while DEQ and the U.S. Environmental Protection Agency on Wednesday conducted a joint monitoring mission. The EPA said it had sent emergency response personnel to the scene to provide assistance.

Ambient air monitors in Port Allen, near the state Capitol, to the north at Southern University and to the south at LSU showed good air quality Wednesday for volatile organic compounds, minute particulates, ozone, sulfur dioxide and nitrogen oxides. Some of those monitors collect air data continuously, some every 25 minutes if triggered, and a few once every six days, unless triggered, DEQ says.

ExxonMobil conducted authorized flaring Wednesday as part of its response to the fire.

Under state rules, companies with emergency incidents must call a Louisiana State Police Hazardous Material hotline within an hour of the event. The Advocate was seeking a copy of that report from State Police late Wednesday. DEQ, which under law is also notified through the hotline, says it received notification through the system. Langley said this initial notification was still being processed before it is made available on the agency's public documents database.

Under state law, companies with air or other releases must submit a report to DEQ within a week, often known as a "7-day report," that details some of the initial facts around the incident, possible causes of the release and the estimated amount of chemicals released.

ExxonMobil said the company employed its emergency alert system to notify the surrounding community. Company representatives also said the fire would not stop gasoline production at the sprawling complex. 

"The gasoline terminal is an entirely different part of the plant. It's still operating and working," Meg Manchester, another ExxonMobil spokesperson, said Wednesday morning. "So this won't have an impact on gas prices."

Stephen Schork, founder and editor of the The Schork Report, a daily newsletter that follows the energy industry, said the plant fire comes at a time when refineries are usually doing maintenance. "Demand is pretty weak at this point," he said.

For the past four weeks, Schork said, the supply of gasoline has been at a record high. That means there would be an ample inventory of gasoline to be drawn upon even if the ExxonMobil refinery had to shut down for an extended period because of the fire. Crude oil prices climbed $1.50 Wednesday, or 3 percent, trading at just under $51.50 a barrel.

The 2,100-acre ExxonMobil complex is a collection of different operations that make plastics, chemicals and a variety of fuels. The refinery alone produces 502,500 barrels per day. It has been the site of other fires and accidental chemical releases in recent history, federal and state regulatory filings show.

A Nov. 22, 2016, fireball severely injured four workers after highly flammable isobutane vapor leaked out and caught fire when vapors reached nearby welding equipment.

The blast drew scrutiny from an array of regulators and prompted nearly $165,000 in fines from the U.S. Occupational Safety and Health Administration. The agency found nine violations of its workplace safety rules — eight "serious" and one "repeat" violation — which generated more than a third of the total fine amount. ExxonMobil is contesting the fines.

The U.S. Chemical Safety Board also conducted an extensive inquiry and found a worker removed the gear box for a "plug valve" to try to open stuck equipment. In doing so, the worker also inadvertently loosened bolts that kept highly pressurized liquefied petroleum gas in a pipeline. 

The CSB didn't find fault with the worker, but found that disassembly of the valve's gear box was an accepted practice at ExxonMobil to open stuck valves, though workers had inadequate training and instruction about how to do it safely. The agency also found the aging valves had had recurring problems.

ExxonMobil told CSB it made equipment and operational changes in response to the incident. OSHA has said ExxonMobil engaged in remediation efforts after the fire.

The refinery had another fire less than year after the 2016 incident, on Nov. 1, 2017, that prompted workers downwind in the aromatics unit to shelter in place for a time, though the incident caused no injuries, ExxonMobil told DEQ. During that incident, nearly 180,000 pounds of unspecified "flammable vapor," 673 pounds of highly flammable mixed xylenes, 647 pounds of carcinogenic benzene and other chemicals were released, according to a report ExxonMobil submitted to DEQ.

More recently, 1,257 pounds of unspecified flammable gas were released last August after an unplanned shutdown of the refinery's hydrocracker, a report to DEQ says. No fire, injuries or offsite impacts occurred.

All those accidents followed the 1989 Christmas Eve explosion that left two dead. That fire involved eight storage tanks that held more than 4 million gallons of oil and lubricants. 

Exxon's buyout program in subsequent years has essentially wiped out what residents said was once a bustling neighborhood across Scenic Highway from the plant entrance. 

Paul Shank, one of the few remaining residents, said he was unaware of the Tuesday night fire until a reporter showed up Wednesday morning and started asking him about it. He said if there was a loud noise or some sort of explosion, he would have heard it.

Shank's house sits on a small lot bordered with chain link fence and padlocks on the gates. All the surrounding lots are vacant, covered in grass with trees planted here and there. He enjoys the peace and quiet.

When the buyouts started, ExxonMobil said it wanted to purchase abandoned and rundown houses simply to clean up the area. But many residents were skeptical of the explanation because the offers weren't limited to properties that could be considered eyesores. Those residents claimed Exxon was trying to create a buffer zone around its plant following the deadly explosion, which damaged buildings miles away.

Shank, 67, said he's aware of the concerns but has come to terms them. He's lived there for about 10 years in a house that's been in his ex-wife's family for decades. 

"I don't have too many years left on me anyhow," said the former U.S. Marine, smiling faintly and surveying the green space beyond his front yard. "I done lived 67 years and seen a lot of others die, so I'm not too worried about it."

Reporters Kristen Mosbrucker and Timothy Boone contributed to this report. 

Email Lea Skene at lskene@theadvocate.com.