FRANKLIN TWP — State police are investigating a one-vehicle crash early Saturday morning that left one man dead and another injured.

Brandon M. Lucas, 33, of Prospect was killed about 2:30 a.m. when the sport utility vehicle he was riding in slammed head-on into a tree along Route 528 near English Oak Drive, authorities said.

“It was one of the hardest impacts I've seen for a while,” said Ken Wilson, chief of the Prospect Volunteer Fire Department.

Jason P. Williams, 44, of Butler, the driver, suffered unknown injuries but he was talking to emergency crews following the crash. A medical helicopter later flew him to a Pittsburgh hospital.

Authorities said Williams was headed south on Route 528 and rounding a bend when he lost control of his Chevrolet Envoy. The vehicle crossed the opposing lane and struck the tree that was on the north side of the highway.

Neither occupant was wearing a seat belt. Firefighters did not know why, given the impact, the vehicle's air bags did not deploy. The SUV sustained severe damage.

A passing motorist called 911 to report the crash.

Butler County Coroner William Young III pronounced Lucas, who was in the front passenger seat, dead at the scene.

A Butler Ambulance Service crew tended to Williams before a LifeFlight helicopter landed on the highway and flew him to Allegheny General Hospital.

He remained hospitalized Sunday and was listed by Allegheny General as being in fair condition, a spokeswoman said.

The road was closed at English Oak Drive north to Christley Road for more than three hours in part to allow a police accident reconstruction team to take photographs and measurements of the scene.