NEW YORK (CBSNewYork) – A doctor of family medicine shot seven people, killing one, before taking his own life at Bronx-Lebanon Hospital Center Friday afternoon.

The gunman was identified as Dr. Henry Bello, 45. He brought an AM 15-type rifle into the hospital underneath a white lab coat, authorities said.

A woman was killed and six other people were hit, five of them receiving serious wounds, according to authorities. One was hit in the leg.

Of the six who were wounded, five were doctors and one was a patient. They suffered gunshot wounds to the chest, abdomen and leg, CBS2’s Andrea Grymes reported.

A hospital spokesperson said it is not believed that Bello knew any of his victims.

PHOTOS: Shooting At Bronx-Lebanon Hospital Center | Witnesses Describe Moments Of Panic

Bello resigned from the hospital in 2015 after allegations of sexual harassment.

He searched for a specific employee before opening fire, sources said.

The gunman opened fire on the 16th and 17th floors at around 2:55 p.m., Police Commissioner James O’Neill said.

It took about 15 minutes from the first 911 call to the time Bello’s body was found on the 17th floor, where most of the shots were fired.

The hospital’s fire alarm system went off during the incident after Bello apparently set two fires — one at a nurses station and a second trying to set himself on fire.

Sources said he ended up going into a room where he shot himself, then staggered out into the hallway where he collapsed.

“[Bello] was let go because I guess they figured he was unstable,” witness Dione Morales said. “He said he was going to do this.”

Morales said Bello made the threat two years ago when he left the hospital.

A “red alert” went off within the hospital during the shooting, which was placed on lockdown. Doctors and nurses barricaded themselves within.

“Everybody said ‘Code red, shut the door, don’t come out of your room.’ Well we got scared, we didn’t know what was going on. They said somebody in the hospital had a rifle,” a patient named Toby told CBS2’s Valerie Castro. “I just heard people screaming and I got scared and they said close your bedroom door and don’t come out of your room. So I closed the door and didn’t come out of my room. My arm is swollen but I pushed the chair to the door so nobody could come in.”

Images posted on social media showed some of the impromptu barriers against the doors.

“People were scared, they were nervous,” Toby added. “I feel very grateful, I’m scared to go back inside.”

One of the gunshot victims was a doctor who had been shot in the hand, witness Gonzalo Carazo said.

“It was scary seeing the blood on the doctors,” Carazo said. “I saw blood on the floor, I saw blood on one of the doctor’s hands.”

“When I heard that my heart started beating and I prayed. I told my pastor to pray for us,” Hilda Mensa said. “I told everybody to pray because we didn’t know what’s going to happen to us.”

“I think about ten people [were in the room].We locked the door and everybody laid down on the floor. I feel so bad because I’m shaking,” Mensa said.

“We heard ‘active shooter, active shooter,'” ambulance worker Robert Maldonado said. Maldonado was on the ninth floor, and said police carried a victim down from the 12th floor. Maldonado, his partner and police officers then carried the shooting victim down nine flights of stairs to the ground floor, he told Castro.

Hospital staffers raced to help the wounded.

“There’s smoke, there’s water, there’s blood everywhere. So you have to wade through that, take care of the patients, remove the rapidly, get them to the operating room, get IVs,” Physician-In-Chief Dr. Sridhar Chilimuri said. “And they did that all while the active shooter was still in the building.”

Mayor Bill de Blasio and Police Commissioner James O’Neill both went to the scene after the shooting.

“Even in the midst of this horror, there were many, many acts of heroism,” de Blasio said, praising the emergency responders. “They put the safety of New Yorkers first, as they always do.”

New York City activated its Unified Victim Identification System. Anyone concerned about the welfare of someone who may have been at the hospital during the shooting and is unable to contact them is asked to call 311. From outside New York City, you can call (212) 639-9675.

Bronx-Lebanon Hospital Center describes itself as the largest voluntary, not-for-profit health care system in the south and central Bronx.

The 120-year-old hospital claims nearly 1,000 beds spread across multiple units. Its emergency room is among the busiest in New York City.

The hospital is about a mile and a half north of Yankee Stadium.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)