GEISMAR — Crews worked Sunday and Monday to restore electrical power in east Ascension Parish and natural gas service in Iberville Parish after an underground natural gas line ruptured early Sunday afternoon, causing an explosion and fire.

Multiple electrical poles caught fire and two feeders were knocked out of service, disrupting power to around 100 customers along River Road between La. 73 south to just outside the Darrow area of Ascension Parish, according to Entergy.

Entergy was working Monday to install new power poles and lines, said Rick Webre, homeland security chief for Ascension Parish. 

"Crews will work as quickly and safely as possible to restore power by late tonight," David Freese, Entergy spokesman, said Monday afternoon.

The loss of power in east Ascension Parish and gas service in east Iberville Parish came as the region braces for another extended cold snap.

The cause of the rupture in the Acadian Gas line, which is owned by Enterprise Products Partners but happened in front of the International-Matex Tank Terminals complex in Geismar, remains under investigation, company, state and local authorities said.

Gas supply to the pipeline had to be turned off to contain the fire, which flared until the remaining gas burned off, Webre has said. The fire started about 1:30 p.m. Sunday and went out about 3:40 p.m. that day, said Rick Rainey, spokesman for Enterprise Products. No injuries were reported from the fire.

State Police hazardous materials officers were not able to see the line break late Sunday because the area where the break happened was still filled with water from fire containment efforts, said Bryan Lee, spokesman for Troop A. 

Enterprise Products officials don't know the cause of the line break yet, Rainey added, but he said he does not believe any kind of excavation or other work in the ground preceded the rupture Sunday. 

Webre, the Ascension official, said he expects the company will do a root cause analysis to find out what happened.

The 20-inch line, which runs along River Road between Ashland Road and La. 73, supplies industrial customers along the Mississippi River, Webre and Rainey said, but also gives gas service to residential customers in eastern Iberville Parish.

Rainey said gas service to east Iberville was restored by 8 p.m. Sunday by diverting gas from another Acadian line while the industrial customers were able to get gas from other sources.

"Until we bring it back up, they will continue to be able to get some natural gas," Rainey said of the industrial customers.

Rainey said he didn't yet know when the broken line will be repaired.

Iberville Parish officials announced in a Facebook post early Monday that gas service was restored, adding that their crews would begin unlocking gas meters and lighting pilots for all customers. If residents are not home when the crews arrive, the workers will leave a card with a phone number to call, officials added.

Follow David J. Mitchell on Twitter, @NewsieDave.