Two people were shot and wounded aboard an MTA bus in Queens Thursday morning when a gunman opened fire from outside, cops and a witness said.

Police said the suspect, who was taken into custody shortly after the shooting at 148th Street and Jamaica Avenue in Jamaica around 9 a.m., was aiming at someone else during a beef on the street that started with a staredown.

“It appears that it was just an exchange of stares that didn’t go well that escalated into a violent confrontation,” NYPD Deputy Chief Jerry O’Sullivan said at an afternoon briefing.

Cops identified the suspect as Melvin Adams, 43.

A single bullet soared through the left arms of two men, ages 20 and 66. They were expected to survive.

“I was on the bus and when it stopped I was about to get out,” the older victim, Jose Gonzalez, told The Post. “I had gotten out of my seat. I was standing up. The doors weren’t open yet when I heard a huge bang.

“‘Boom, boom’ from the front and [it] got me here,” he said, pointing to his left shoulder,” I felt the burn. I was hit.”

He said passengers began screaming and rushed to get off the bus. 

Gonzalez, who was headed to a doctor’s appointment, was released from the hospital but said the other victim remained hospitalized. 

Deputy Inspector Vincent Tavalaro, commander of the 103rd Precinct, said at the briefing that Adams ran from cops but was Tased and arrested with the help of an off-duty cop who was coming off her shift.

“She put her life on the line without her vest and was there in the line of duty to help apprehend [the suspect],” Tavalaro said. “Recovered in that book bag, which was safeguarded by the off-duty officer, was a semi-automatic firearm.”

He said Adams allegedly fired a total of three shots.

A witness told The Post that the victims were on a Q8 bus that was pulling into the stop when a man ran up and opened fire into the bus. The bullet pierced the windshield, opposite the driver’s side.

Afia Noshin, who was on the bus, told The Post she was sitting in the back when the gunfire erupted.

“I had my headphones on,” she said. “I heard a gunshot. I think saw like haziness. People started screaming. The doors were still closed. Everyone was shouting, ‘Open the door, open the door, let us out.’ They opened the door and we ran out.”

Adams was filmed by The Post leaving the 103rd Precinct on 91st Ave. — wearing a black Polo Ralph Lauren t-shirt, black cargo shorts extending below his knees, and bright red high-top basketball sneakers.

He was handcuffed behind his back and also had cuffs around his ankles.

“I’m innocent,” Adams maintained when asked why he shot at those people as he was taken away by police officers.

Additional reporting by Amanda Woods and David Meyer