It happened just before 2:30 a.m. at Blackstone and Rialto avenues in north Fresno.
The driver told police he had a tire blowout, which caused him to lose control of the vehicle and hit the hydrant, a signpost and a man.
The driver says he did not know he struck the man until after the collision.
The driver remained on the scene and is cooperating.
Police say alcohol does not appear to be a factor in the crash.
The victim was taken to the hospital with injuries to his leg and head.
That lane was closed off until the water problem was fixed.