SILSBEE, Texas — A woman and her five children were killed in a fire that quickly engulfed their Texas home, authorities said Wednesday.

Flames were already shooting from the home near Silsbee, about 80 miles northeast of Houston, when a neighbor called 911 about 12:15 a.m., Hardin County Sheriff Mark Davis said.

The home, a small structure converted at some point into a residence, was fully engulfed when firefighters arrived, Davis said. He said all six bodies were found in the home after the blaze was extinguished, and the family was likely sleeping when they were overcome by heat, flames and smoke.

“It gives the appearance of being a very fast-moving fire,” said Davis.

Davis did not release their names because officials were still working to notify family members of the deaths. However, family pastor Randy Feldschau identified the dead as Ashley Pickering, 31, and her children: Camden, 3; twins Cash and Cavence, 4; Serenity, 7; and Cristian, 11. The twins’ 5th birthdays were to have been next week.

The children’s father, who didn’t live at the home, was distraught when he arrived later, said Davis, who described the scene as “horrific.”

“It’s a very emotional task and our hearts, first and foremost, go out to the family,” the sheriff said. “But we’re also looking at our first-responders, especially our firefighters. It’s a very difficult situation to be dealing with deaths like this that include so many children.”

The cause of the fire is under investigation, but Davis said it doesn’t appear to have been deliberately set.

“We’re not seeing anything at this point to give us cause that it’s suspicious,” he told The Associated Press.

Relatives of the victims live in a house in front of the burned home, but it wasn’t damaged.