Police received several calls at 4:27 a.m. from people who had heard gunshots in the area of the 22000 block of Seventh Street.
Officers arrived and found an unresponsive man in his early to mid-20s, police said. Medical personnel from the Hayward Fire Department pronounced the man dead at the scene, police said.
The location remains an active crime scene, with investigators still looking for clues and attempting to identify witnesses, police said.
Anyone with information about the death is asked to call Inspector R. Lampkin at (510) 293-7079, Inspector G. Jakub (510) 293-7081, or Hayward police at (510) 293-7000.