Marvin Harrison Jr. collapses on the field and leaves the game after a header hit in the Cardinals-Packers game

Arizona Cardinals wide receiver Marvin Harrison Jr. collapsed on the field and left Sunday’s game against the Green Bay Packers after accidentally hitting his head on a pass play.

The game took place in the second quarter. Cardinals quarterback Kyler Murray targeted Harrison with a pass over the middle. Packers cornerback Jaire Alexander broke up the pass and threw Harrison to the turf. As Harrison fell, the crown of his helmet hit Packers linebacker Isiah McDuffie in the thigh, causing his head to snap back.

Harrison stood up after the hit, visibly dazed. He immediately fell back onto the grass.

He went to the medical tent on the sidelines and then went to the locker room with the coaches. The Cardinals announced before halftime that he was being diagnosed with a concussion but did not immediately rule him out.

An injury would be a tough blow for Harrison in his sixth NFL game and for a Cardinals team that has struggled to move the ball. As a first-round rookie in Week 5, Harrison was Arizona’s top receiver with 17 catches for 279 yards and four touchdowns. The Cardinals went into halftime trailing the Packers 24-10.

This story will be updated as more information becomes available.