NEW YORK (CBSNewYork) — An off-duty New York State narcotics agent is facing charges following a shooting that injured two people on a crowded Upper West Side street Friday night.

“We just heard a pop and she just keeled over,” said witness Wendell Santiago.

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Santiago told CBS 2’s Janelle Burrell he’s still in disbelief after a 31-year-old woman collapsed right outside of the juice shop he works at on the corner of Amsterdam Avenue and West 82nd Street.

“We thought it was a BB gun at first. Then we saw the actual bullet and the whole investigation, so it was actually pretty crazy,” Santiago said.

The shooting happened at around 9 p.m. during the dinner rush. The sidewalks were packed with pedestrians and diners when witnesses said they heard a piercing noise.

“I thought it was fireworks,” said one witness.

The crowd scrambled for cover.

“We heard a pop, and then we saw cops outside. They had their guns drawn and everybody started running and we just got down on the floor,” said witness Carolyn Frankel.

Police said the gunman was 49-year-old Victor Zambrano, an off-duty New York State narcotics agent who was apparently drunk when his weapon fired, striking the woman in the ankle, Burrell reported.

As WCBS 880’s Jim Smith reported, Zambrano allegedly gave the woman the gun to look at and there was a struggle when he wanted it back, causing the gun to go off.

“She was actually kind of shocked. It happened so quick as didn’t even know what happened. She just looked and saw her foot was bleeding and her boyfriend saw that she was bleeding and that’s when he went off running after the guy,” Santiago said.

However, witnesses told CBS 2’s Dave Carlin she was just a bystander as Zambrano and another man fought over the gun.

According to witnesses, the woman’s boyfriend chased the suspected shooter a block north to 83rd Street. That’s when the gun went off again, striking the 42-year-old boyfriend in the shin, Burrell reported.

Moments later, police caught up with the suspect and took him into custody.

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Cell phone video obtained by CBS 2 shows officers surrounding the man who allegedly fired the shots.

“I could see an armed policeman draw a gun and pin a man to the front of the bar,” said one witness.

“We saw the police arrive and apprehend the first gentlemen and then take the second guy on the stretcher into the ambulance,” Melanie Bieber said.

Witnesses told Carlin that before the arrest, the off-duty agent seemed to be “out of it.”

“Stumbling, couldn’t walk a straight line,” witness Adam Tosto said. “Some police officers came with their guns drawn, said ‘drop it, drop it, drop it.’”

Those who know the arrested officer describe him as a friendly, family man who lives nearby.

“He’s a good person that I know, very good person,” friend Gaspar Figueroa said.

“Great guy, humble, quiet, friendly, so I was surprised. Very surprised,” Dimitri Vezyrakis said.

Police recovered the weapon at the scene.

Zambrano is facing charges of assault, criminal possession of a weapon, resisting arrest and reckless endangerment.

However, his arraignment was pushed back after he suffered an undisclosed medical emergency while inside the 20th Precinct station house.  A sheet was used to cover him as he was wheeled out of the station house and into an ambulance.

When doctors give the OK, he will be moved from the hospital to court to face a judge.

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