A man killed Monday morning when his Cadillac crashed into an oak tree on Highway 36 -- about 16 miles north of Cross Plains -- has been identified.

Dr. Thomas Allan Woodward, 64, was pronounced dead at the scene at 10:17 a.m., a Texas Department of Public Safety news release said. Woodward wasn't wearing a seat belt, the release said.

Woodward was driving his four-door Cadillac south on Highway 36 in Callahan County when the vehicle left the roadway and struck the tree, DPS said. The crash happened about 1.3 miles north of U.S. Highway 283.

There were no skid marks, the roadway was dry, and alcohol or drugs weren't believed to have been a cause of the accident, authorities said.