PITTSBURGH—Leonard Weiss was sleeping in on Saturday morning at his home in the city’s Squirrel Hill neighborhood after working late at the University of Pittsburgh Medical Center Mercy when he was awoken by a loud noise.

“I thought it was construction,” said Weiss, an emergency medical services director at UPMC. “It was rhythmic like that.”

Then the noise got louder. Weiss heard screaming and then police sirens from multiple directions.

“I thought, ‘It can’t be automatic gunfire,’” he told The Daily Beast.

It was the sound of an AR-15-style semi-automatic rifle blasting away at the Tree of Life synagogue where an anti-Semitic gunman killed 11 people. Weiss turned on his police radio and heard the names of streets near his home.

He called Ronald Roth the chief of UPMC’s Emergency Medical Services Division, who was in a wooded area 10 miles outside outside the city training students in responding to medical emergencies in the wilderness.

Roth had already gotten a notification on his pager about a potential active shooter.

“I hope this is bullshit,” Roth told Weiss over the phone.

“I hear gunshots,” Weiss responded.

Weiss, 33, said he thought he might die. He thought the shooter could venture into a home, maybe his, looking for cover. He made the decision to exit his door into what could be a hail of gunfire. That’s just what emergency docs do, he said; the worst situations are the ones where doctors are most needed.

“It was in my motivation to do the job I do,” he said.

Weiss threw on pants, a t-shirt and boots and grabbed a medical kit. He walked out and saw police officers taking cover behind their vehicles.

“I could see the uncertainty in everyone’s eyes,” Weiss recounts.

He identified himself as an emergency medical physician, but a police officer told him he didn’t look like one, before Weiss explained he walked over from home. A cop escorted him down the street to wait for gunshot victims.

Weiss didn’t know this at the time, but the man had already shot several congregants, moving through multiple rooms. He had also engaged in a gunfight with the first police to respond near the entrance. He had an assault rifle and three Glock handguns.

Miles away, Roth drove to the scene with his own police radio on. Roth heard, “shots fired, shots fired,” he said. He considered the possibility that his colleagues were being killed. “Oh, my God, I know a lot of paramedics, I know a lot of police officers,” he thought.

Not only that, Roth grew up in Squirrel Hill and had his bar mitzvah at Tree of Life and attended Hebrew school there. He was pretty sure his classroom was on the third floor — where the gunman barricaded himself to fight off police.

When Weiss arrived, the gunman was still in building. There was calamity on the police radio, until a voice declared that the shooter had barricaded himself on the third floor. Stationed down the street, Weiss followed the reports from the gun battle on the police scanner. Before the shooting was over, the suspect shot three officers and a fourth was injured by breaking glass.

Finally, Weiss heard the suspect was shot. Then he surrendered.

“Then he became a patient,” Weiss said.

When Roth arrived, he reported to the command post established by the EMS workers on the scene two blocks away from the synagogue, the nearest location considered safe; police were mostly certain the incident was over when the gunman surrendered, but they had to eliminate the possibility of a second shooter or an explosive device before EMS could enter the synagogue.

Roth immediately ran through a scenario where a massive number of victims would need to be transported in a short amount of time. He would need to touch base with the hospitals.

“Obviously, we knew the city so we knew the hospitals,” Roth said. “Knowing the potential if there were many victims, we could overwhelm them.”

He also realized that they needed as many ambulances as possible. “We needed to call some in from outside the city.” He called them in. Few of the ambulances were needed, though: there was nothing paramedics could do for most of the people shot. The coroner’s office took over responsibility for them.

Roth took on a supervisory role at Tree of Life and watched startled EMTs exit the building. It was like something out of movie, they told him, with dead bodies strewn about the floor. Six people, including the four police officers, were transported out with injuries.

Roth, Weiss, and other first responders had to figure out where to transport Robert Bowers, the alleged gunman. Police decided he should be the last of the injured out of the building, Weiss said. Medics and police made the joint decision that Bowers should not go to any of the hospitals where the four officers were being treated. There was a trauma center in Pittsburgh where none of the others had been transported: Allegheny General. That’s where Bowers was hospitalized for gunshot wounds.

Weiss stayed at the scene where FBI agents interviewed him.

Having faced a mass casualty tragedy, Weiss said he doesn’t know if he fully lived up to the training.

“There’s no way to prepare emotionally and sometimes even organizationally,” Weiss said. “You do the best you can.” He said part of the skillset of trauma medicine is becoming “ingrained” in a team of colleagues that can react swiftly and procedurally in such a situation.

Roth says he was impressed by the skill of the EMTs. Everyone—from orthopedic surgeons from anesthesiologists—acted as one, performing different functions for a greater goal under an unimaginably stressful situation. “They acted heroically,” Roth said. “I was so impressed.”

Before Roth left the synagogue for a hospital, he glanced at the door. It was desecrated by bullet holes.