The operator of a Q train recalled the moment he tried to save a straphanger who was critically injured during a random shooting on the subway in Lower Manhattan on Sunday morning.

“I went to work expecting to do my regular job, not expecting to be [the] first person to a shooting, trying to help a person who was shot,” the operator, Luis Irizarry, said in a statement.

The victim, 48-year-old Daniel Enriquez, was discovered lying in a pool of blood by Irizarry after passengers alerted him to the scene. The operator then attempted to perform chest compressions.

“We’re not trained for that,” he said about the first aid tactic. “How can we mentally prepare for something like that?”

Enriquez was shot by a complete stranger in the last car of the northbound Q train around 11:42 a.m. as the subway crossed the Manhattan Bridge.

Once the Q train crossed the bridge and pulled into the Canal Street station, a witness to the shooting pulled the emergency breaks.

Irizarry said he got off the train at the station to investigate and noticed panicked straphangers shouting “He has a gun” and “Someone got shot.”

The operator walked to the last car and saw the victim bleeding from the chest on the train floor.

“As I got to the last car, I saw a gentleman lying on the ground with a gunshot wound to his chest,” he said. “He didn’t appear to be breathing. His chest wasn’t moving up and down.”

Irizarry, who has no formal CPR training, said he attempted to revive the man who was left lying alone in the panic.

“Nobody was helping him, so I got down and pushed down on his chest, giving chest compressions,” he said. “I’m not a trained EMT but I was trying to help this man.”

He continued to give the man chest compressions to no avail until police and paramedics arrived at the scene.

The victim was rushed to Bellevue Hospital where he was pronounced dead.

Irizarry’s coworker, the train’s conductor Walstein Chapman, called rail control to inform them of the shooting.

Chapman tried to keep panicked commuters calm and directed them to alternate subway routes.

“We did what we had to do,” he said. “My heart is still racing but I had to do what I had to do.”

Meanwhile, the gunman — described as a heavyset man with a beard — fled when the train pulled into Canal Street. He ran up the stairs out of the station to Centre Street, police officials said. He remains at large.

TWU Local 100 President Tony Utano praised the two men for remaining calm in the aftermath of the shooting.

“The Train Operator and Conductor are rattled and traumatized by today’s violence, but they handled the incident and the aftermath calmly and professionally,” he said in a statement. “They deserve the city’s thanks and praise. We’re very proud of them.”