Two New York City police officers were fatally shot by a single gunman “execution style” on Saturday afternoon.

The gunman has also died, reportedly from a self-inflicted gunshot.

The officers were sitting in a marked patrol car in the Bedford-Stuyvesant neighborhood during an overtime shift as part of an anti-terrorism drill, the New York Post reports.

Shortly before 3 p.m. the gunman approached the patrol car from the passenger side and opened fire at point-blank range.

According to one witness who spoke to The New York Times, one of the officers appeared to have been shot in the head.

NYPD deputy chief Kim Royster told The Times “it looks like they were shot in the upper body.”

The Post reported that both officers had died.

“It’s an execution,” a law enforcement source told the paper.

OMG – RT @KTLA: Raw video shows NYPD shooting investigation; 2officers shot “ambush-style,” http://t.co/0Cy42SoVjn pic.twitter.com/dK3NQtgWmJ — Susan Cooper (@BuzzEdition) December 20, 2014

According to other Post sources, the gunman fled into the subway and was pursued by police. He reportedly fatally shot himself.

The shooting comes amid a recent wave of anti-police sentiment following the deaths of Michael Brown and Eric Garner, two black men killed by white police officers.

Brown was fatally shot in Ferguson, Mo., in August. Garner died in July when a NYPD officer put him in a choke hold during an arrest attempt.

When neither officer was indicted, protesters hit the streets. Some anti-police violence has also occurred.

In October, 32-year-old Zale Thompson attacked NYPD officers with a hatchet before being fatally shot. Thompson’s attack was labeled an act of homegrown terrorism after it was revealed that he had terrorist sympathies.

There have been other reports of groups putting out bounties on police officers. There is no indication yet on what motivated Saturday’s shooter.

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