The murdered men are 41-year-old Colin Samuels, 35-year-old Jason Spencer, 35-year-old Sheldon Simmons and Joel Pompey.
Samuels was shot in his red Nissan X-trail in Port of Spain when he stopped at a traffic light near Bath Street, East Dry River at 4:30pm.
The shots caused Samuels to crash his vehicle into a parked car, as the attacker fled the scene.
He was taken to the Port of Spain General Hospital where he was pronounced dead on arrival.
At the same time in San Juan Joel Pompey, of Seventh Avenue, Barataria, was standing at the corner of Sunshine Avenue and Bagatelle Road in San Juan at when he was shot several times by an unknown assailant.
He was rushed to the Eric Williams Medical Sciences Complex, Mt Hope where he was pronounced dead on arrival.
His killer escaped.
An unknown assailant also killed Jason Spencer while he was walking home.
Spencer was walking along the roadway in the vicinity of Gerbera Drive and Petunia Avenue, Morvant, when he shot by the man who was sitting on a brick.
Spencer was killed instantly.
No motive was given for his shooting