The 49ers confirmed Smith was involved in an incident but didn't elaborate on how he was hurt. The team described the second-year pro's injuries as "minor."
Smith was treated for his injuries and was released from a local hospital, according to Comcast SportsNet BayArea.
"We are in contact with Aldon, and thankful that his injuries were not more serious and that he is recovering comfortably," 49ers general manager Trent Baalke said in a team-issued statement. "The 49ers are also in communication with local authorities as they gather information regarding the incident, and will reserve further comment at this time."
The Santa Clara County sheriff's department, which wouldn't confirm if Smith was at the party, said two people were wounded from gunshots and one was stabbed, according to The Bee.
A source, however, confirmed to The Associated Press that Smith suffered stab wounds.
Smith, the No. 7 overall pick in the 2011 NFL Draft out of Missouri, appeared in all 16 games as a rookie last season. He recorded a franchise-rookie record 14 sacks, most among NFL rookies, and also forced two fumbles.
Smith also was arrested this offseason for DUI in January in Miami Beach, Fla.
UPDATE: Smith is believed to have suffered stab wounds to his shoulder and abdomen, likely from a small pocket knife, while trying to break up a fight at the party, CSN Bay Area reported.
"It was pretty chaotic when law enforcement arrived," Sgt. Jose Cardoza said, according to the San Francisco Chronicle. "There were at least 100 people, and there was a lot of alcohol involved. Everyone was confused, everyone heard gunshots, heard commotion, but nobody knew where the gunshots were coming from. Amongst all the chaos, there were a couple of gunshot victims in the crowd and a stabbing victim."
UPDATE: Smith thanked the well-wishers via his Twitter account Sunday morning.