Police say the 42-year-old man victim driving on Utica Avenue in the B46 bus lane when he was shot once in the head at around 8:30 p.m.
The gunman walked up to the van, fired one shot and walked away.
After the victim was shot, his van coasted about three blocks on Utica Avenue, coming to a stop only when it crashed into another vehicle.
He was rushed to Kings County Hospital, where he was pronounced dead.
The gunman fled in another vehicle. No arrests were immediately made.