Immigration officials say that Bovino, who was not wearing a helmet, was struck in the head by a rock. One protester who filmed the encounter disputes that he was hit.

U.S. Border Patrol Commander Gregory Bovino is under intensifying scrutiny in Chicago after he was recorded on Thursday throwing what appeared to be a tear gas canister at protesters, leading attorneys to accuse him of violating a temporary restraining order that bans the use of tear gas, pepper spray and other tactics against journalists and protesters unless under imminent threat.

The Department of Homeland Security said in a statement that Bovino was struck in the head by a rock thrown by “hostile and violent” protesters, though several witnesses challenged that contention.

On Friday, Bovino was ordered to appear before a federal judge on Tuesday.