DPS officials are trying to figure out how a man ended up dead inside a submerged vehicle early Saturday morning.

Around 3:30 a.m., Fort Bend County Sheriff's officials said they got a call from a man who seemed to be out of breath.

When the lost contact with the man, officials said they tracked his cell phone to a location on Old Richmond Road near Tranquil Drive in Fort Bend County.

That's when, officials said, they found a vehicle under water with a dead man inside.

DPS officials were called to the scene and have taken over the investigation.

Officials said it didn't appear the severe weather played a role in the crash.

Investigators believe the driver failed to make a curve in the road when he drove into the water.

Troopers are now looking into whether the driver was asleep at the wheel or intoxicated.