Referee Armando Villarreal was hit by an object—thought to be a bottle of water—thrown from the crowd as he went to check video replays during Atlanta United's clash with Minnesota United on Tuesday.
Minnesota were 1-0 up with nearly an hour played at Mercedes-Benz Stadium when goalkeeper Kyle Reynish came charging out of his area and caught Abu Danladi.
Villarreal then went over to check the replay to determine what action should be taken when an object came flying out of the crowd and struck him on the head.
The incident was captured on Twitter:
Atlanta Journal Constitution reporter Doug Roberson said the official had been hit by a bottle of water:
Villarreal did not appear to be injured and continued with his duties, awarding Minnesota a free kick on the edge of the area and handing Reynish a red card.