According to a news release from the Los Gatos Monte Sereno Police Dept., police arrested Foster after receiving a call regarding a possible disturbance. After making contact with Foster and the victim, police took Foster into custody without incident after their initial investigation.
Foster was transported to Santa Clara County Main Jail and bail was set at $75,000. He was released from custody Sunday night, per jail records.
The incident remains under investigation.
A league spokesman told NFL Network's Tom Pelissero the league is aware of Foster's arrest and will look into the incident. Foster could be subject to potential NFL discipline under the league's personal conduct policy.
The arrest is the second for Foster in the last month. The 31st overall pick in the 2017 NFL Draftwas booked on Jan. 13 in Alabama on a possession of marijuana charge and was later released after posting $2,500 bond.
Niners general manager John Lynch told NFL Network's Steve Wyche after drafting Foster they had no concerns about the linebacker's character: "We were exhaustive in getting to know the kid. We met him at the combine. We had him out here for a visit. [Coach] Kyle [Shanahan] and I spent a lot of time on the phone with him Facetiming ... He's going to be disappointed [with being picked No. 31] because he feels he was one of the better players."