The assailant opened fire at Bronx Lebanon Hospital in New York City on Friday afternoon, killing at least one person before apparently taking his own life, authorities said.

Police Commissioner James O'Neill told reporters a female doctor was pronounced dead at the scene. Six other people were being treated for gunshot wounds in the emergency ward - five of them in a serious condition.

Local media citing police sources identified the suspect as Dr. Harry Bello, a 45-year-old family medicine physician who used to work at the hospital. Police said he had returned to the facility with an assault rifle hidden underneath a white lab coat. 

Speaking at a press conference, New York Mayor Bill de Blasio said the shooting appeared to be an isolated incident and was not terror related.

"This was a horrible situation unfolding in a place that people associated with care and comfort, a situation that came out of nowhere," de Blasio said.

How it unfolded

Emergency services were called to the scene after gunfire erupted at around 2:50 p.m. local time (1850 UTC) on the 16th and 17th floors of the hospital. The building was surrounded by police cars and fire trucks and police could be seen on the roof with guns drawn.

"I thought I was going to die," Renaldo Del Villar, a 55-year-old patient who was in the emergency room, told The Associated Press. "When there's a shooter and you don't know where the shooter is, you don't know what's going to happen."

Police officers went floor to floor looking for the suspect and reported just before 4 p.m. that he was dead inside the hospital.

"One shooter is deceased at the hospital," New York Police Department spokesman J. Peter Donald wrote on Twitter.

Commissioner O'Neill said the suspect had tried to set himself on fire, setting off an alarm, before turning the gun on himself.

The 120-year-old hospital has one of the busiest emergency rooms in New York City. Two people were killed there in 2011 in what police described as a gang-related shooting. 

aw,nm/kl (AP, Reuters, dpa, AFP)