The Oakland Athletics are investigating an “incident” with a security guard during last night’s game against the Giants, video of which appears to show the guard striking a fan.

A brief video of the situation was captured from the stands by Twitter user Shane Siegrist, who has since made his account private. The video appears to show a security guard repeatedly punching a woman before pulling her to the ground by her hair, while other guards unsuccessfully try to separate the two.

The A’s issued a statement mid-game, acknowledging that there was an “incident” they were investigating and saying that the team does not condone violence—and noting that security doesn’t work for the team.

Here’s additional video from elsewhere in the upper deck, showing security and police flooding the area afterward: