Officers responded to a 4:11 p.m. emergency call about an injured man in the 500 block of Cottage Park Drive, west of Mission Boulevard, police said.
They found the victim suffering from a gunshot wound to the torso, police said. He was pronounced dead a short time later at a local hospital.
The police do not have any suspects in the killing, but said a preliminary investigation suggests that this was not a random act of violence.
The death marks Hayward's 12th homicide of the year, police said.