NEW YORK (CBSNewYork) – One of the victims in the deadly Bronx-Lebanon Hospital shooting is filing a lawsuit, and reliving the terrifying moments.

“I was certain I was going to die. Every breath I took I could feel more blood collecting in my lungs,” said Dr. Justin Timperio.

On June 30, 2017, Timperio was on the 16th floor of the hospital. He looked up from his work and saw a former hospital doctor, Henry Bello, rushing through the door in a white lab coat. He says then Bello started shooting.

“I saw flashes of light coming from the muzzle of the gun, smoke, large pops,” Timperio said.

People were ducking under desks. First responders flooded the scene, CBS2’s Marc Liverman reported.

“I looked down and I realized I had been shot. I saw blood coming out of me,” Timperio said.

At a news conference Tuesday, Timperio and his attorney took reporters back to those terrifying moments, announcing a lawsuit against the hospital for not taking enough security measures to protect everyone inside.

“To keep the people that go there safe, to keep the employees to go there safe,” he said.

The lawsuit goes on to say the hospital failed to take away Bello’s identification when we was forced to resign back in 2015.

Upseate Guns and Ammo, a gun dealer, is also listed in the lawsuit. Timperio’s attorney Arnold Kriss alleged the seller never conducted an adequate background check, selling Bello an AR-15, the rifle he used to kill a doctor and injure six others. Timperio was shot in the liver.

“The last thing I remember was asking the nurse to give me some pain medication so I could die without pain,” Timperio said.

As he got further away from the shooter and closer to safety, Timperio described one of the last things he saw.

“He dropped a match on the nursing station and a wall of flames essentially climbed to the ceiling. I was certain he was going to burn the building down,” he said.

Timperio’s life was spared, but he worries his injury could affect his future ability to work as a doctor.

CBS2 reached out to both defendants listed in the lawsuit, but they declined to comment.