A police report obtained by NFL.com from the Hillsborough County (Fla.) Sheriff's office stated Foster was booked into jail at 11:11 p.m. ET on a first-degree misdemeanor domestic violence charge. Foster was arrested by Tampa police at 9:10 p.m. at the Grand Hyatt hotel, where the team is staying before playing the Tampa Bay Buccaneers on Sunday.
A judge granted Foster $2,000 bail during an initial court hearing Sunday morning and he was released from jail. The judge also ordered him to have no contact with his accuser.
"I can tell you it's extremely disappointing for me, for Kyle Shanahan], for ownership, for everyone in here," [49ers general manager John Lynch said Sunday morning. "Because we care a lot about Reuben. I can tell you that it was a situation where we laid out some very specific ground rules for Reuben, as we do for all of our players. We have a set of standards in place that the players were involved with in developing. In this case, it was communicated exceptionally clear and to the point as to what we expected out of him.
"Unfortunately, what transpired yesterday -- this isn't a comment on what happened there because it would be mere speculation on our part -- it's more of a comment on him not living up to what we communicated; to the energy, to the time we've invested into him. That doesn't mean we don't love him. We all do, we care for him. But we feel it's in the best interest of our organization to move on at this point, and that's a very tough decision. I want to be clear this is an organizational decision. Kyle and I talked last night, we brought it to ownership, and we were all lock-step in the decision. It was not easy on anybody."
The victim told police that during a verbal altercation with Foster, he slapped her phone out of her hand, pushed her in the chest area and slapped her with an open hand on the right side of her face. Officers observed a one-inch scratch on her left collarbone, according to police.
During their initial investigation of the incident, officers learned Foster and the victim lived together in the past and they were involved in an on-again-off-again relationship over the past three years. Police confirmed the victim is the same one who accused Foster previously of domestic violence against her in February before recanting.
Foster faces potential discipline from the NFL following his latest arrest. "Even in instances in which a club releases a player such as this, the league will review the matter," NFL spokesman Brian McCarthy said in a statement.
Lynch and coach Kyle Shanahan said in April following a previous arrest for Foster on domestic violence charges that were eventually dropped that the team had a zero-tolerance policy on the issue.
"I care about Reuben," Shanahan said after Sunday's loss to the Tampa Bay Buccaneers. "I don't think it's just black and white [on] all of this. And neither was last time [he was arrested]. I believed him a lot on last time. If that was true [the accusations initially made against him last time], then it would be easy and he wouldn't have been on our team. The courts took care of that, but there was also a lot of other things that he had made bad mistakes on, bad decisions and things that we needed him to follow by. And he struggled with that. And we helped him a lot with it.
"He's gotten better in that way, but it's been too much. We care about Reuben, but no one is more important than this team. The No. 1 rule is you got to protect the team and he's put us in a bad light too much. Hopefully this will fix him and he'll be a success somewhere else."
Foster's career in San Francisco ends after just 16 games with the team. Foster is expected to be officially placed on waivers Monday.
Foster was charged in January in Alabama with second-degree marijuana possession. That charge was eventually dismissed after he completed a first-time offender diversion course.
Foster then faced more serious charges for an incident in California in February. He was initially charged in April with felonies for domestic violence, making criminal threats and weapons possession after being accused of beating up his ex-girlfriend.
He was sentenced to two years' probation, 232 hours of community service, and $235 in fines. He will not be allowed to own guns while he's on probation.
After the charges were dropped, Lynch said Foster was told he would have to continue to earn his place on the team with his behavior.
Foster was suspended the first two games of the season for violating the NFL's conduct and substance-abuse policies.
Foster has struggled on the field this season as well as he has dealt with shoulder and hamstring injuries. He had missed the past two games with a hamstring injury and is listed as questionable for Sunday with the injury.
Foster had 29 tackles in six games this season with no sacks, forced fumbles, fumble recoveries or interceptions.
The Associated Press contributed to this report.