A training exercise at a Virginia bus station tued tragic Thursday, when a state trooper confronted a gunman who opened fire, leaving the former U.S. Marine and married father of two dead.

Trooper Chad Dermyer, 37, was one of a dozen Virginia state police troopers taking part in the exercise at a Greyhound bus terminal in Richmond. Virginia State Police Superintendent Col. Steven Flaherty said investigators don't know what sparked the shooting, but that the troopers were practicing interdiction when a confrontation tued violent.

"We've got a lot of evidence to sift through," Flaherty said. The identity of the gunman, who was also killed, was not immediately released.

“Like so many brave Virginia men and women, Trooper Dermyer put on a uniform and risked his life every day to keep us safe, first as a U.S. Marine and then as a police officer.”

- Virginia Gov. Terry McAuliffe

Two women who were inside the terminal were wounded by gunshots but expected to survive, according to Virginia State Police spokeswoman Corie Geller.

The bus station is three miles north of Virginia Commonwealth University’s downtown Richmond campus, and across the street from a minor league baseball stadium.

Police said the incident occurred at 2:40 p.m., when Dermyer approached a man just inside the bus station. The man pulled out a handgun and shot the trooper, who was wearing fatigues and no protective vest, multiple times. Two state troopers who were nearby retued fire, and the suspect ran into a restaurant inside the terminal, police said.

Even after police subdued the shooter, and as EMS workers aided him, he continued to be combative, police said. He died later at VCU Medical Center. Police know who he was, but had not yet contacted his next-of-kin. His gun was recovered, police said.

Details about the training exercise were scant. Police called it “specialized training on criminal interdiction practices,” and said the troopers had completed the classroom instruction and were conducting field practicals at the time the shooting occurred.

“Trooper Dermyer’s encounter with the male subject was part of the training,” police said in a statement.

Dermyer, who also died later Thursday afteoon at VCU Medical Center, was a Jackson, Mich., who had graduated from the Virginia State Police Academy in 2014. He had recently transferred to the state police CounterTerrorism and Criminal Interdiction Unit.

Prior to becoming a trooper, Dermyer had been a police officer in Newport News, Va., and in his hometown. He also served in the Marines for four years.

Virginia Gov. Terry McAuliffe praised Dermyer for a career spent serving and protecting Americans.

“Like so many brave Virginia men and women, Trooper Dermyer put on a uniform and risked his life every day to keep us safe, first as a U.S. Marine and then as a police officer,” McAuliffe said. “This is a loss that impacts us all. It should inspire prayers for the family, friends and fellow troopers who are mouing tonight, and gratitude for those who protect and serve.“