A woman and her three children were pronounced dead on the scene of a fiery crash in South Texas Sunday morning.

The accident happened about 12 miles northeast of George West, 60 miles northwest of Corpus Christi.

Deputies say Joannie Lopez, 22, of George West, was driving the SUV when it went off U.S. 59, hit a tree and burst into flames.

DPS says the crash also killed 2-year-olds Christopher and Alonzo Lopez, and 3-year-old Andrew Lopez Jr. The woman’s husband survived but suffered a broken left arm and left leg.

Investigators said the woman was the only person wearing a seat belt and driver fatigue may have played a factor in the deadly wreck.