Police are seeking a second suspect who may have been involved in the attempted robbery that led half a dozen officers to open fire outside a Queens cellphone store earlier this week, killing Detective Brian Simonsen.

"There’s somebody else that we’re looking for, I don’t want to go too deep into it," said Police Commissioner James O'Neill during a Friday morning appearance on “The Joe Piscopo Show." He didn't offer more details, but said that detectives were actively looking to apprehend "anybody that was involved in this."

Simonsen, a 19-year NYPD veteran, was killed on Monday night while responding to reports of an armed robbery at a T-mobile store in Richmond Hill. Six more officers arrived at the scene, firing 42 rounds after a suspect emerged from the storefront waving an imitation pistol, police said. Simonsen was killed in the barrage of bullets, and his partner Sgt. Matthew Gorman suffered a leg injury.

"We don't know who shot who at this point," said Chief of Department Terence Monahan during a Wednesday afternoon briefing on the investigation. "It was a really chaotic scene."

The suspect, 27-year-old Christopher Ransom, was also shot, and is expected to survive. He's been charged with murder, aggravated manslaughter, robbery, assault and menacing, and is expected to be arraigned from his hospital bed. Ransom, who friends say is autistic, is a self-identified prankster who's been arrested for a host of non-violent crimes, including impersonating a police officer and repeatedly sneaking into a Downtown Brooklyn courthouse, where he reportedly worked as an intern five years ago.

In his radio interview, O'Neill said that the incident had sparked a review of police training protocols, with recommendations forthcoming "to make sure this doesn't happen again."

"You can have the best training in the world, but when you respond to a job of an armed commercial robbery, you’re thinking about a lot of different things, you’re talking to your partner," he said. "A lot of people responded to that. We just have to take a good look at this."

The NYPD is continuing to review body camera footage obtained by officers at the scene.

There will be a wake for Simonsen on Long Island on Monday and Tuesday of next week, followed by a funeral on Wednesday.