Problems with a heating system at Valero Energy Corp.’s refinery in Meraux caused a loud noise that awakened some nearby residents early Monday, a company spokesman said.

Bill Day said the St. Bernard Parish facility had a problem with a heater in its benzene unit just after 5 a.m., which caused the noise.

“People in the area heard it, and it woke some people up,” he said.

The incident did not lead to a release of emissions that exceeded allowable levels, and no injuries were reported, Day said.

“There were no off-site effects other than the noise, which people heard,” he said.

The cause of the incident was still under investigation Monday afternoon, he said.

The incident was reported by the company at about 5:40 a.m., said Jean Kelly, a spokeswoman for the Louisiana Department of Environmental Quality.

Kelly said there was “a small backfire and some smoke associated with it” but added that the area was “immediately secured.”