A New York City detective known since childhood as “Smiles” for his bright, welcoming nature died in a hail of police gunfire as officers faced off with a robbery suspect who had a fake gun and a long rap sheet that includes an arrest for pretending to be a cop, authorities said Wednesday.

Detective Brian Simonsen was struck once in the chest Tuesday night when he and six other officers fired 42 times as suspect Christopher Ransom charged toward the entrance of a T-Mobile store in Queens and simulated pulling the trigger of his imitation handgun, police said.

Another officer, Sgt. Matthew Gorman, was shot in the leg. The shooting started as he and two uniformed officers retreated from the store when Ransom, 27, emerged from a back room and came at them, Chief of Department Terence Monahan said. Gorman is in stable condition.

“You have to understand, this happens in seconds,” Monahan said. “It goes from 0 to 60. You’re investigating a possible crime and all of a sudden someone is charging at you, pointing what you believe to be a firearm, simulating firing at you. It raises everything very quickly.”

Five officers captured parts of the scene on body cameras, Force Investigation Division Chief Kevin Maloney said. Investigators are also reviewing surveillance footage from the store. None of the video has been made public.

Ransom was wounded and is hospitalized in stable condition.

He has been arrested at least 11 times since 2012, records show, and he was wanted by police in connection with a Jan. 19 robbery at another cellphone store.

Ransom was charged in 2016 with impersonating a police officer after allegedly climbing over a gate and walking up to a desk at a Brooklyn police station while wearing a fake SWAT vest and police badge. Police records list his alias as “Detective.” Ransom pleaded guilty to criminal trespass and was sentenced to 20 days in jail.

Four years earlier, he pleaded guilty and was sentenced to jail time for pretending to be an intern to gain access to a judge’s chambers and later violating an order to stay away by flashing a photocopied identification in an attempt to gain access to the courthouse.

This is Christopher Ransom, the suspect who brandished an imitation gun while robbing the Queens cell phone store where our hero detective was killed last night. He’s in custody, but we want anyone with information about him that might help our investigation to call #800577TIPS. pic.twitter.com/Aoc3Ug3Q6U

— Chief Terence Monahan (@NYPDChiefofDept) February 13, 2019

Ransom sued the city over a 2015 disorderly conduct arrest, alleging officers approached him on a Brooklyn street corner for no reason, cornered him in a food store with guns drawn and took him to a psychiatric ward against his will.

The charges against Ransom were later dismissed, and Ransom dropped the lawsuit in 2016. A message was left for Ransom’s lawyer in the lawsuit.

Simonsen, 42, grew up on the east end of Long Island, and he and his wife continued to live close by — more than an hour’s drive from the 102nd precinct where he worked his whole 19-year NYPD career. At Riverhead High School, he played football and baseball and was friends with everyone he met, childhood friend Melissa Weir said.

“Everyone is in complete shock. Everyone is feeling this,” Weir said. “When you have somebody like Brian, it’s really hitting everybody. There are people all over the place hurting.”

Simonsen should have been off Tuesday for a union meeting, but he opted to go to work so he could continue tracking a string of recent robberies, Detectives’ Endowment Association president Michael Palladino said.

“He was the one that you called if you had a problem,” @NYPDChiefofDept says about hero Detective Brian Simonsen who was killed in the line of duty. “He was a 19-year veteran who spent his entire career in the @NYPD102Pct. There wasn’t a person in the 102 who didn’t know Brian.” pic.twitter.com/pFmf9ZXr4W

— NYPD NEWS (@NYPDnews) February 13, 2019

Police swarmed to the T-Mobile store at around 6:10 p.m. Tuesday after a 911 caller standing outside reported seeing the suspect — dressed in all black and carrying a duffel bag — take two employees to a back room at gunpoint, according to dramatic dispatch audio .

“No sirens, guys,” a dispatcher warned.

Simonsen and Gorman, who were both in plainclothes, were working on another case nearby when the call came and arrived around the same time as patrol officers, O’Neill said. At first, the front of the store appeared empty, he said.

Gorman and two uniformed officers went inside, but quickly retreated when a man matching the suspect’s description emerged from the rear of the store pointing at them what appeared to be handgun, Monahan said.

“Shots fired! Shots fired!” an officer is heard yelling on the dispatch audio moments later, over a barrage of gunshots that blew out the store’s doors, showering the sidewalk with glass.

Simonsen stayed outside as Gorman and the uniformed officers went in, Monahan said. Simonsen fired two of the 42 shots. Gorman fired 11 times. It’s not clear who fired the shots that struck them, Monahan said.

About a minute later, according to the dispatch audio, Gorman tells dispatchers that he’s been hit, and an officer screams for dispatchers to rush an ambulance to the scene.

Covers of Wednesday’s NY Daily News & NY Post following friendly fire tragedy of NYPD Detective. pic.twitter.com/T6VJGFWlFU

— NYC Scanner (@NYScanner) February 13, 2019

Join us in our vow to #NeverForget @NYPD102Pct Detective Brian Simonsen and the sacrifice he made for our city. Fidelis Ad Mortem – @NYPDnews #BlueLivesMatter #HERO #RIP pic.twitter.com/AtgIvdUZCG

— NYC Scanner (@NYScanner) February 13, 2019

(AP)