The NYPD officer who was killed outside a Bronx housing project early Sunday morning during a struggle with an allegedly armed suspect was fatally shot by his fellow officers, police say. Mulkeen is the second NYPD officer this year killed in the line of duty, and also by friendly fire.

According to NYPD Commissioner James O'Neill, Officer Brian Mulkeen, 33, was shot twice by his fellow officers as he wrestled on the ground with the suspect, 27-year-old Antonio Williams, outside the Edenwald Houses.

In a press conference at NYPD headquarters on Monday afternoon, O'Neill said that Mulkeen was wearing plainclothes and a bulletproof vest, and that the officer fired his weapon five times, but that it's unclear if any of those bullets hit Williams.

Mulkeen's fellow officers fired a total of 10 rounds, two of them hitting Mulkeen, O'Neill said. It's not yet clear how many rounds hit Williams, who was pronounced dead at the scene. According to the Medical Examiner's office, Mulkeen was shot in the head and the torso.

“It was a violent struggle. And from start to finish, from first round to last round, was 10 seconds. Just think about that. Think about how quick that is,” O'Neill told reporters.

“This is a tragic case of friendly fire. But make no mistake, we lost the life of a courageous public servant solely due to a violent criminal who put the lives of the police and all the people we serve in jeopardy,” O'Neill said.

Police said they found a .32 caliber handgun at the scene that belonged to Williams, but that it had not been fired. The Commissioner said that of the six total officers present, five had their body cameras turned on; Mulkeen "did not have the opportunity" to activate his.

On Sunday, NYPD Chief Terence Monahan said that Mulkeen and his colleagues in the Bronx Anti-Crime Unit were on a routine patrol and attempted to question Williams "because of gang activity, which included recent shootings in the area." Williams ran, and Mulkeen chased him, and the two ended up wrestling on the ground. Police said that body cam footage showed Mulkeen yelling, "He’s reaching for it. He’s reaching for it."

In February, Detective Brian Simonsen was fatally shot by his fellow officers while responding to a robbery in Queens. The suspect in the robbery turned out to be carrying a fake gun, and the eight officers at the scene reportedly fired 40 rounds.

After Detective Simonsen was killed the NYPD issued a video of new training guidelines on responding to commercial robberies. Asked if the death of Officer Mulkeen will prompt more changes, Commissioner O'Neill replied, "As I've said many times before, in every incident that happens in the NYPD there is the opportunity to learn and to move forward and to get better at what we do."

O'Neill added, "There is video available, we can learn from this and move forward. As I said in my opening statement, this is an absolute tragedy. Again, it was caused by a convicted felon carrying an illegal loaded firearm."

Police said the investigation into the shooting is ongoing, and Commissioner O'Neill said that the body camera footage captured in the shooting would eventually be released.