The MTA workers who rushed passengers to safety after a madman opened fire in a subway car described Friday when they realized there’d been a mass shooting — and how they jumped into life-saving action.

 The employees said they notified agency crews around 8:30 a.m. Tuesday that there’d been a shooting onboard after desperate passengers started banging on the window to the train’s cab in Brooklyn.

“There’s a shooter! We need help!” the passengers screamed, train conductor Raven Haynes recalled to reporters.

Train operator David Artis admitted, “I thought they were just knocking on the door to find directions.

 “If they wasn’t banging on anything, I might think that nothing had happened,’’ he said.

As soon as the Manhattan-bound N train pulled into the 36th Street station, Haynes quickly opened the doors so the passengers could escape — and Artis got to work tending to the injured and rushing the unscathed to safety.

“I locked my cab and ran out to the platform, and a passenger who was coming off the train fell onto the floor,’’ Artis said during a proclamation ceremony at City Hall, where Mayor Eric Adams honored his and the other workers’ heroism.

The shooting left 29 people hurt, including 10 with gunshot wounds.

“I went to check to see if anybody else was in that car. … Blood [was] on the floor,’’ the train operator said.

Artis recalled that as an R train came into the station across the platform, he shouted to commuters, “Get on the train! Get on the train! Get on the train!”

Little did he know, one of those passengers was suspected shooter Frank James, who allegedly blended in with commuters and boarded the R train to escape. Artis said he never saw him.

Back on the platform, Artis told the injured to “stay calm, police and medical” are on the way and directed military veteran Thomas Fischer to assist a man who’d been shot in the knee.

Artis then peeked back into the train car and radioed Rail Control again.

“I look back in the car on the floor where the suspect left his luggage, and I see bullet casings on the floor,” Artis recounted.

“I told Control, ‘Look you gotta get police here ASAP, there’s bullet casings on the floor.’”

Haynes said, “When you see people in danger, especially when you are a frontline employee, your first thought is to make sure that your passengers or whomever you’re dealing with is safe.

“My whole point was to make sure my riders were OK. At no point did I think about my own personal safety, I just wanted to make sure that my passengers were safe, they were calm and they physically got out of the area as quickly and safely as possible.”

Outside the station, bus operator Parla Mejia was about three and a half hours into her shift driving the B37 when she looked out her window and saw passengers, many of them high-school-age children, running for their lives.

“I didn’t know what happened. … I saw plenty [of] students, teenagers, maybe about 20 or 30 of them, just running towards my bus,” Mejia recalled.

“I left the doors open, and they [loaded in]. … I squeezed as many passengers as I could on that bus. I told them, ‘If you could put three in the seat, let me get you guys safely to the end where you can pick up a shuttle to get where you’re going,’ ” she said.

“I was trained that if there’s a crisis and my bus is available, make it available, so I picked up all the passengers and escorted them.”

She soon learned from other passengers that there’d been a shooting, and, “That’s when my adrenaline kicked in.”

“I was like, ‘OK, let’s go. we got this. Let’s get on the move here.’ That day, I worked from 5 in the morning until midnight, skipped my meal, and I kept the buses moving,” Mejia recalled.

“My thoughts were to keep my passengers calm because they were crying, they was screaming. ‘Keep them calm.’ As long as I remain calm, I could control them.”

Some of the children, distraught from the incident, sobbed “uncontrollably,” so Mejia soothed them and assured them they were on their way to safety.

“ ‘Please call your parents, let your parents know where you at. Give them my bus number,’ ” Mejia told the kids.

“ ‘Give your mother my name. Tell your mother my name. Tell her that you’re safe and I’m gonna take you to the next bus.’ ”

Adams awarded Haynes, Artis and Mejia with mayoral proclamations for their heroism. Train operators Joseph Franchi and Michael Catalano and conductor Dayron Williams, who were manning the R train that brought passengers to safety, also were hailed in proclamations.

“When our city was attacked Tuesday morning, you risked real danger to save the lives of everyday New Yorkers,” Adams told the workers.

“When bullets were flying, 33 to be exact, you stayed calm, stayed focused, and you saved lives. … Thanks to you, no passenger was left behind. No lives were lost. Thanks to you, our city keeps running every day, day after day.

“You all personified what’s great about our subway system and our MTA system overall,’’ the mayor said.

Later, during an unrelated press conference, Adams was asked about James and the mental-health programs he received in the past while living in The Bronx, which the suspect railed about in a series of YouTube videos he posted before the shooting.

Instead of addressing the question, Adams continued to point his finger at social-media companies for hosting the vitriolic videos.

“We’re going to be sitting down, speaking with social-media industries and [telling] them they must play a better role in policing their sites,” Adams said.

“Social media must step up and play a better role in not continuing to fester and using it as a platform to continue to fester some of the anger that we witnessed in this incident of the shooting.”