NYPD Chief of Department admitted there were still plenty of unanswered questions about Tuesday night's fatal shooting of a detective in Richmond Hill, Queens, where a veteran cop was killed because of friendly fire.

Monahan said, "We don't know who shot who at this point. We know it was a chaotic scene."

It was a chaotic scene indeed. The NYPD says seven officers fired 42 shots at a robbery suspect pointing what turned out to be a fake gun. Detective Brian Simonsen was hit in the chest by one of those bullets from a fellow cop.

The head of the Force Investigation Division, Deputy Chief Kevin Maloney said, "The perpetrator makes his way right up to that front door. He holds up his hand with the firearm in his hand and he simulates that he is firing at the police officers.  Then he retreats back into that store as the shots are being fired."

Police received a 911 call that a masked gunman was robbing the T-Mobile store on Atlantic Avenue and 120th Street. Detective Simonsen and Sergeant Matthew Gorman arrived together about the same time as six uniformed officers did.

As the suspect, Christopher Ransom, approached the cops, police say some officers ended up to the right of the store and others to the left. The shooting lasted just 11 seconds. Detective Simonsen was caught in the crossfire. No one knew Ransom's gun was a fake.

(27-year-old Christopher Ransom has been arrested at least 11 times since 2012, records show, and he was wanted by police in connection with a January 19 robbery at another cellphone store. Photo courtesy of the NYPD).

Maloney said, "We have five officers whose body worn cameras captured part of this incident. Those body worn cameras along with additional surveillance that has been recovered from inside a store are currently under review."

As the NYPD continues to investigate, it says it does know that Detective Simonsen fired two shots and Sergeant Gorman fired 11 times.

Gorman was hit once near his ankle. As of Wednesday afternoon, the other officers had not been interviewed by investigators about where they were standing and what was going through their minds.

The chief of department, Terence Monahan said officers are taught ways to avoid friendly fire situations.

Monahan explained, "Every six months, when you go to the range and you get trained, we talk about the tactics. We talk about instances that have occurred in the course of the last six months. You want to avoid that crossfire situation. But understand this it is great to train but everything happens in a second.  You are reacting in seconds and you are in fear of your life, your adrenal is high. We try our best to train and we will continue to train. It is our job to try to keep our officers safe."

Another part of the investigation: why Detective Simonsen and Sergeant Gorman, who were in plainclothes were not wearing  bulletproof vests. The NYPD says all officers are supposed to wear them.

Menatime, Christopher Ransom has been charged with murder, manslaughter, assault and robbery.

Simonsen's wake is being held Monday and Tuesday at the Church of Saint Rosalie in Hampton Bays on Long Island.

His funeral is set for Wednesday morning.