More than 200 residents packed a western Pennsylvania church Wednesday night to hear from the company that owns a pipeline that exploded last month. The crowd, at times edgy, posed questions about the explosion and pipeline safety to four Spectra Energy officials over a period of two hours.

The officials called the blast “unacceptable” and apologized for the explosion, which badly burned one man and destroyed his home.

“I am truly, truly sorry that this event occurred,” said Randy Putt, a local area manager for Spectra. “My thoughts and prayers are with the injured individual. I can’t get him off of my mind.”

The explosion in Westmoreland County occurred 200 yards behind the house of 26-year-old James Baker. Baker fled the home just before it burned down. He suffered third-degree burns on three quarters of his body.

At Wednesday’s meeting, residents asked about the company’s safety rating, its response time to the incident and the age of the pipeline that exploded.

The 30-inch line is part of the company’s Texas Eastern Transmission line, a 9,000-mile complex of high-pressure pipes that carry gas from the Gulf Coast to the Northeast.

The company says investigators are looking at whether a coating may have led to corrosion on the outside of the pipe.

After a resident asked how often the company had checked the pipe, Andy Drake, Spectra’s Vice President of Environment, Health and Safety, said it was inspected by an in-line device called a ‘pig’ four years ago. The device inspects the pipeline from the inside.

“What did the pig miss? We’re not sure that the pig missed this or what the pig’s role in this was. We do know that the coating had something to do with it,” Drake said.

Drake said the company has since looked for sections of the same line with a similar coating and shut them down. The line begins in Delmont, Pennsylvania—a few miles from where the blast occurred—and ends in New Jersey.

Anywhere we saw a pattern that looked similar to the pattern we saw here—with the coating type present and any other contributing factors that look the same–we have shut that pipe down,” Drake said. 

Another resident asked what could have ignited the gas once a breach of the pipeline occurred.

Tom Wooden, Spectra’s Vice President of Operations, said he didn’t know.

“The exact ignition source isn’t known. From some of the observations, the pipe failed, gas started escaping and it found an ignition source,” Wooden said. 

The pipeline failure resulted in the release of an undetermined amount of natural gas, which ignited and caused a crater 30 feet wide, 50 feet long and 12 feet deep—and burned a section of a field measuring a quarter mile in radius.