CONNOQUENESSING TWP — A 25-year-old man was on his way home from a methadone clinic Monday morning when he crossed into oncoming traffic and caused a collision that killed the other driver on Route 68 in front of the Connoquenessing Elementary School, state police said.

Investigators believe the suspect, Justin Enslen, was impaired and had a suspended license for a previous drunken driving conviction, said Lt. Eric Hermick.

“He was at fault,” Hermick said of Enslen.

Mark Bishop, 52, of Oakland Township died in the crash about 10:35 a.m. Butler County Coroner William Young III pronounced him dead at the scene. An autopsy was planned for Monday afternoon.

Bishop's sister, Holly Merkner, 41, of Lyndora, a passenger in his Nissan Frontier, was taken by ambulance to Butler Memorial Hospital, authorities said.

Police did not consider her injuries serious.

An ambulance took Enslen to Allegheny General Hospital in Pittsburgh with “non-life-threatening injuries,” police said.

Enslen, who lives in Connoquenessing Township not far from the crash site, was eastbound on Route 68 when his Dodge Ram pickup truck veered into the opposite lane.

“Witnesses reported that he abruptly swerved into the oncoming lane,” Hermick said. “(Bishop) had no time to react.”

The impact of the crash crumpled in the front driver's sides of both vehicles.

Connoquenessing volunteer firefighters had to use a Hurst tool to free Bishop from his mangled Nissan.

He was apparently still alive when rescuers got there. However, he died soon after a Life Flight helicopter, called to fly him to a Pittsburgh hospital, landed in a field across from the school.

Police went to the hospital and spoke to Enslen after the crash.

He told investigators that he was driving back from a regular visit to the methadone clinic in Cranberry Township, Hermick said.

Methadone is a prescription narcotic mostly known as a treatment for heroin addiction.

The hospital took blood from Enslen for medical purposes. Hermick said police plan to obtain a search warrant for the suspect's medical records, including toxicology results.

While not immediately arrested, police said, Enslen could face a maximum charge of homicide by vehicle while driving under the influence. Under state law, the charge is punishable by a minimum of three years in prison.

Enslen, who has an extensive criminal record, was convicted of DUI by a minor in 2006. He was sentenced to 2 to 4 days in county jail and just less than 6 months on probation, Butler County records showed.

In 2009, he was convicted of felony drug possession, and sentenced to 2 to 5 years in state prison.

The force of Monday's collision was enough to leave a massive debris field that covered both lanes and stretched for 50 feet or so.

“I was doing the dishes and heard a bang,” said Kayla Greygor, who lives next door to the school. “I came outside and heard this screaming.”

The screaming was coming from Enslen.

“He was asking, “Why?' Greygor said. “He was in a lot of pain.”

There was no school Monday because of the Presidents' Day holiday. But three employees were working at Connoquenessing Elementary, and they all heard the wreck.

“I heard it, and I said to myself, 'What the heck was that?'” said groundskeeper Ray Duncan, who was in his truck in back of the building.

He, too, heard Enslen screaming. “He was panicked over what happened,” Duncan said.

Witnesses reported that numerous motorists stopped to help the injured in the two vehicles. Both engines were smoking.

Shortly after the collision, Enslen and Merkner were able to get out of their vehicles with help from others.

The pickup ended on the south berm of Route 68, the Nissan on the north berm partially on the school's lawn. Both vehicles were facing east after the crash.

Hermick said police do not believe speed was a factor in the crash. The speed limit on that portion of Route 68 is 55 mph.