A man was shot dead in Brooklyn on Sunday afternoon as he cycled through a quiet residential neighborhood.

The unnamed man, 31, was found unconscious and unresponsive at the corner of Union Street and Utica Avenue in Crown Heights just after noon beside his bike and bloody baseball cap.

Witnesses describe seeing a gunman approach and fire a single bullet into his head before jumping into a gray Chevy Suburban and speeding off.

A man was shot dead in Brooklyn on Sunday afternoon as he cycled through a quiet residential neighborhood

Police have described the shooting as ‘a well-planned execution’ and are unsure if the gunman had an accomplice.

Witness Jacob Ramlall, 34, said he saw the man fall and also someone yelling.

'You did not hear a shot. [It was] like he used a silencer of something,' he told the New York Post.

Another witness noted that the killer 'was very quick jumping out of the car’ to shot the victim.

Another witness to the shooting was in their car and followed the suspects’ speeding getaway car for a couple miles before losing sight of it.

There have been no arrests at this time and the investigation is still ongoing.

The unnamed man, 31, was found unconscious and unresponsive at the corner of Union Street and Utica Avenue in Crown Heights just after noon beside his bike and bloody baseball cap

Less than 2 hours later and just 2 miles away, a 19-year-old man was shot once in each leg.

The wounded man was taken to Brookdale Hospital in stable condition but refused to cooperate with investigators.

The shooting is believed to be part of an ongoing beef between two rival gangs in the neighborhood.