A woman fatally shot herself in the head while driving south on Interstate 75 Thursday morning, police said. The bizarre incident was one of two grisly fatalities in Cobb on Thursday, as authorities were also investigating an earlier accident on Sewell Mill Road, where a man was killed in his burning Jeep after he collided with trees.

The female, said to be approximately 60 years old, shot herself while traveling in the far left lane of I-75 just south of North Marietta Parkway around 10:50 a.m., Marietta Police spokeswoman Officer Jenny Murphy said. Her 2007 Toyota Camry then struck the median wall and came to a stop. The suicide did not cause any other accidents, Murphy said. The woman, whose name was not released pending notification of family, was alone in her car.

"This is unusual and we are fortunate that no one else was injured," Murphy said. "This could have been a very deadly incident."

Two lanes were shut down during the investigation, but traffic returned to normal within a couple hours, Murphy said.

The other fatal crash happened about 2:40 a.m. in east Cobb.

Cobb Police say a 21-year-old Marietta man, Kyle Ray Bryant, driving a 2000 Jeep Grand Cherokee eastbound on Sewell Mill Road, attempted to negotiate a curve, but his vehicle ran off the road and into trees in the front yard of a home not far from the intersection with Old Canton Road.

The fuel tank on the Jeep ruptured and caught fire. The driver, Bryant, was dead at the scene.

Cobb Police investigators can be reached at (770) 499-3987.