SUNNYVALE -- A Sunnyvale man who was shot multiple times Saturday evening after allegedly charging at an officer with a hammer died later that night at Stanford Hospital.

The man was taken to Stanford for surgery but was pronounced dead at the medical facility late Saturday, according to the Sunnyvale Department of Public Safety.

Police on Monday were not releasing the man's name, pending an autopsy by the Santa Clara County Coroner's Office. Few additional details about the shooting were available Monday, and Sunnyvale police Capt. David Verbrugge said it "could be a few days or a few weeks" before the results of the investigation are available. Early reports indicated the man was in his 20s.

Sunnyvale police Capt. Doug Moretto said the shooting occurred not long after 6 p.m., when two officers arrived at a residence on Tartarian Way in response to 911 calls that a man was assaulting his mother.

As the officers approached the scene, Moretto said, they found a man who matched the description of the person involved in the assault. He said the man was standing in the street near the intersection of Tartarian Way and Middlebury Drive and was holding what appeared to be a hammer in his hand.

Moretto said one of the officers approached the man and told him to stop what he was doing and to drop the hammer.

The officer and his partner, who was nearby, told investigators the man refused and allegedly charged the first officer, who shot the man several times in self-defense, Moretto said.

Both officers immediately gave the man first aid, and called for an ambulance, which arrived and took the man to Stanford.

The last officer-involved shooting in Sunnyvale occurred in September 2007, when two Sunnyvale Public Safety officers shot and killed a 32-year-old man who was wanted on suspicion of murder.

The officer involved in Saturday's shooting is a 14-year veteran and was placed on administrative leave per department policy. Sunnyvale detectives are conducting the investigation, under supervision of the Santa Clara County District Attorney's Office.

Staff writer Eric Kurhi contributed to this report. Contact Mark Gomez at 408-920-5869. Follow him on Twitter @MarkMgomez.