RICHMOND -- A 33-year-old Sacramento man was in serious condition after being shot three times outside his grandmother's home Sunday afternoon, police said.

Officers responded about 1:30 p.m. to a single-story home in the 100 block of South 20th Street for a reported shooting and found a man suffering from three gunshot wounds, said Lt. Darren Monahan. The man had been shot once in the chest, once in the ankle and once in the buttocks, but was expected to live.

The victim, whose name was not released, was taken by medical helicopter to John Muir Medical Center in Concord.

A preliminary investigation revealed the man, who was visiting his grandmother, was standing in the driveway near the garage with two other men when an unknown male suspect walked up and began shooting at the group.

Three bullets hit the victim, but the other two men were not injured. An elderly man inside the home was also not injured, police said.

Following the shooting, the suspect ran south on South 20th Street and then west on Florida Avenue.

A motive was not immediately known and as of 5:20 p.m. no arrest had been made, police said.

Anyone with information about the shooting is asked to call police at 510-620-6643.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.