A Pennsylvania State Police corporal clung to life Tuesday after he was shot three times during a gunfight with a motorist he'd tried to arrest for driving under the influence, authorities said.

The trooper underwent surgery and was in "extremely critical" but stable condition after a routine traffic stop escalated into a violent altercation on a highway in Plainfield Township, Northampton County, about 65 miles (104 kilometers) north of Philadelphia, said state police Capt. Richard D'Ambrosio.

He said he is "very hopeful" the trooper will survive.

"He's a warrior. He went through a heck of a fight out here along the side of the road. He has a will to live, and, God willing, he is going to pull through this," D'Ambrosio told reporters outside a hospital in Fountain Hill, where the trooper was flown for treatment.

The trooper works at the Belfast barracks. His name was not immediately released.

He had ticketed the motorist for speeding Tuesday morning and was about to pull away when the motorist flagged him down, wanting to discuss the citation and how he would pay it, authorities said.

The corporal began to suspect the motorist was under the influence of drugs or alcohol, called for backup and performed a sobriety test. The troopers then tried to arrest the motorist, who began resisting, D'Ambrosio said.

"The troopers were in a knock-down, drag-out fight along the side of the road with vehicles speeding by them, and it got very, very violent," said D'Ambrosio, who viewed video of the altercation.

At some point, the suspect broke free, ran to his car, retrieved a gun and began shooting, striking one of the troopers, he said. Both troopers returned fire, hitting the suspect several times.

The motorist fled in a blue Pontiac sedan and drove himself to Easton Hospital. He was later transferred to another hospital, where he underwent surgery.

The suspect's name was not released. Authorities planned to release more information on Wednesday.

State police gathered evidence from suspect's car, which was parked near the emergency room entrance of Easton Hospital and appeared to have its rear window shot out. It was later put on a flatbed and driven away.

Gov. Tom Wolf said in a statement that he and his wife were "praying for this trooper, the family and every member of the Pennsylvania State Police."