Two brothers, ages 12 and 11, and their 13-year-old sister died at the Whispering Oaks Trailer Park in Houma, said District Chief Lance LaMarca of the state Fire Marshal's office.
The children's parents and five other children, were taken to a Baton Rouge burn unit, LaMarca said.
The trailer was engulfed in flames when firefighters arrived about 2:30 a.m. Wednesday, Houma Fire Inspector Mike Millet said.
The children's father rescued one child after smoke came under his bedroom door, but was unable to get the other three because the fire spread so quickly, LaMarca said.
The dead children's father was the most severely burned, LaMarca said, followed by their mother. He said all the survivors are expected to recover.
The mother and another child escaped through a window, while relatives sleeping in another bedroom at the opposite end of the mobile home got out through a back door.
LaMarca said the deceased children and their parents were visiting from Alabama for Christmas, and there were 12 people in the trailer.
LaMarca said there was severe damage to the combination living room-kitchen where the children had been sleeping. He said the occupants were using space heaters and candles, which could have caused the fire. The damage was so severe, however, that it might be difficult to rule out other causes, such as electrical appliances in the nearby kitchen, he said.
There were no working smoke alarms in the trailer, LaMarca said.