Houma, La. – Two young brothers who were burned on more than half their bodies in a house fire remained in critical condition Monday as Terrebonne Parish government workers dug up a gas line near the rubble of their home.

Tom Bourg, parish utilities director, said the line may have caused a fire and explosion Sunday that leveled the home at 300 Railroad Ave. He refused to discuss his findings in detail, citing an ongoing investigation.

“It appears to have been a natural-gas explosion or gas related,” he said. “It’s premature to come to any conclusions.”

Sia Theriot and her sons, Julian and Jia McGuire, ages 3 and 4, respectively, were in the home when the fire began, relatives said. Theriot was stable Monday evening at Baton Rouge General Burn Center while her sons remained in critical condition.

Charles Aubert, Theriot’s father-in-law, said he smelled gas inside the home Sunday and checked pilot lights on the heater and kitchen stove. All were lit.

He left the home and, from less than a block’s distance, heard an explosion. He returned to find Theriot and her sons escaping their burning house.

The boys had third-degree burns on about 60 percent of their bodies, said Rose Mary Johnson, 51, their aunt. They began breathing on their own Monday and responded to voices.

Both remained sedated because of pain, she said. Their recovery is expected to take months.

Theriot was burned on her face, back and arms, Johnson said.

Houma firefighters responded to the house at about 2 p.m. and battled flames for about six hours, authorities said.

The house, reduced to charred debris, was picked over by investigators. Mike Millet, a Houma Fire Department inspector, said there were no signs it was intentionally set.

Bourg gathered with other officials, including Parish Attorney Courtney Alcock, as a workers broke through the street to access a gas line. They pulled out a long piece of pipe and photographed it.

Alcock was called to the scene “in case there is any litigation,” she said.

Residents said the officials refused to give them information about the fire. Many said they believe a gas leak is to blame.

Lester Galmore, who works as a maintenance man for a day care center next door to the house, said he believes gas was the cause because of the effort workers went through to reach the line.

“But the city is never going to say that,” he said.

Aubert, who lived in the house with his son, Jonathan McGuire, the father of the boys, said he occasionally smelled gas outside.

A gas meter was changed on the house Saturday, he said. The street’s gas lines were replaced in the past month.

“A regular fire wouldn’t have done that,” he said of the explosion. “It had to be natural gas.”