New York, Dec 21 (IANS): Two New York police officers were shot dead by a lone gunman in Brooklyn Saturday, apparently to avenge the death of African-Americans Eric Garner and Michael Brown at the hands of white police personnel.

According to investigators, it was an execution-style mission, the New York Post reported.

The New York City Police Department (NYPD) officers were working overtime as part of an anti-terrorism drill when they were shot at point-blank range, in their heads, according to the report.

“I'm putting wings on pigs today,” a person believed to be the gunman wrote on Instagram in a message posted just three hours before the officers were shot through the front passenger window of their car.

The post included an image of a silver automatic handgun with a wooden handle.

Another post showed camouflage pants and blue sneakers, which matched the clothing the dead gunman was wearing as his body was carried away from the scene on a stretcher.

“They take (one) of ours... let's take (two) of theirs,” the post added.

The gunman fled to a nearby subway station, where, as pursuing police personnel closed in, he shot himself, sources said..

“I heard shooting -- four or five shots,” said Derrick McKie. “It sounded like from a single gun,” he said, adding that ambulances and police cars rushed to the scene.