Two police officers in New York City died on Saturday after a man walked up to their patrol car and shot them "execution style" before he fled and fatally shot himself.

The NYPD officers, Rafael Ramos, 40, and Wenjian Liu, 32, were in a patrol car Saturday afternoon in the Bedford-Stuyvesant neighborhood in Brooklyn when 28-year-old Ismaaiyl Brinsley shot four rounds into the vehicle, killing both of them. In a Saturday evening press conference, New York City Police Commissioner William Bratton said that the officers had been deliberately targeted.

"They were, quite simply, assassinated, targeted for their uniform and the responsibility they embraced," Bratton said. "Both were ambushed and murdered."

Bratton added that Brinsley, the main suspect, was found dead of a self-inflicted gunshot wound at a nearby subway station.

According to USA Today, Bratton indicated that Brinsley approached the police car from the passenger side and shot his weapon several times. He added that Liu and Ramos "never had an opportunity to draw their weapons" and had been "killed with no warning, no provocation."

"They may have never even seen their assailant, their murderer," Bratton said.

The New York Daily News reported that prior to the killing, Brinsley asked two men to follow him on Instragram. NYPD Chief of Detectives Robert Boyce noted that Brinsley inquired about the men's gang affiliation.

"He then said, 'Watch what I'm going to do!'" Boyce said.

However, Boyce added that the two men, based on interviews by detectives, probably had nothing to do with the attack.

The police commissioner told reporters that Brinsley shot his former girlfriend at a Maryland residence, injuring her. According to USA Today, Bratton said that Brinsley's comments from the victim's Instagram account indicated that he had a "very strong bias against" police.

New York City Mayor Bill de Blasio told reporters that Saturday's shooting was an attack on all New Yorkers.

"When a police officer is murdered, it tears at the foundation of our society. It is an attack on all of us," said de Blasio. "When they are attacked, it is an attack on the very concept of decency."

Saturday's shooting has also exposed a deep rift between the New York mayor and the NYPD. According to New York Daily News, the head of the Patrolmen's Benevolent Association, Patrick Lynch, asked police officers to sign a petition that would prohibit de Blasio from attending their funerals if they died in the line of duty.

"The police unions have been angry at the mayor for not giving them sufficient support after a Staten Island grand jury opted not to indict a cop in Garner's July 17 chokehold death," New York Daily News stated.

New York Daily News reported that Ramos' grieving family joined community leaders for a prayer vigil on Sunday close to their Brooklyn home.

"I would like to thank all those who have shared their sympathy and support for our beloved family member, Rafael Ramos, who will always be loved and missed by many," Lucy Ramos, the aunt of Ramos, said in a distraught manner.

Despite the rift, Ronnie Gonzalez, a cousin of one of the slain cops, indicated that the mayor is more than welcome to attend Ramos' funeral.

"He could come (if he wants)," Gonzalez said. "We're not disrespectful. We're not going to throw him out and say don't be here. If he wants to come and show us some support, by all means we will accept that."

According to USA Today, the shooting comes at a time when American police tactics are being criticized following widely publicized deaths of unarmed black men. The NYPD has said that although Brinsley was black, the officers were of Latino and Asian descent.