LEBANON, Ind. -- A Boone County sheriff's deputy was injured early Friday in a rollover crash while on patrol, police said.

Lt. Jeff Keller, 46, rolled his department-issued car in the 2800 block of north U.S. 52. just after 3 a.m., said Deputy Chris Burcham.

A witness said that Keller's vehicle left the roadway and hit a drainage culvert in the median, rolling several times and coming to a rest on its top in the northbound lanes.

Keller had to be freed from the vehicle, and was transported to Witham Hospital with head injuries. He was released a few hours later.

Burcham said police don't yet know what caused the crash, but said Keller was wearing a seat belt.

"We are very happy that Lt. Keller was not seriously injured in his crash," said Boone County Sheriff Ken Campbell. "This is a good example of how wearing your seat belt drastically reduces your injury.

Keller is a 22-year veteran of the department, Burcham said.