The Kansas City Chiefs and Detroit Lions got into a brawl in the waning seconds of their “Sunday Night Football” clash in Week 6.

The fight started after Lions safety Brian Branch threw an open-handed punch at the face of Chiefs wide receiver JuJu Smith-Schuster after the Chiefs took a knee to seal a 30-17 victory.

It wasn’t clear what precipitated the punch. Branch walked straight up to Smith-Schuster following Mahomes’ final kneel-down, ignoring an offered handshake from the quarterback to go up to the veteran receiver.

Like Mahomes, Smith-Schuster offered his hand for Branch to shake, as the NBC broadcast showed. But Branch instead decided to throw the punch before being restrained and led away by Chiefs running back Isiah Pacheco.

As that was happening, an irate Smith-Schuster began chasing down the 23-year-old safety and landed an open hand to his facemask as well. The two continued to jostle through Pacheco before the trio all ended up on the ground.

Shortly thereafter, the two teams all surrounded the fighters, creating a scrum. Eventually, order was restored, but not before another member of the Lions – whose number could not be identified – was thrown to the ground after landing a blow to Pacheco’s face.

The officials did not intervene in the brawl. They merely surrounded the teams briefly before heading to the locker room with the game finished.

(This story will be updated as more information becomes available.)

This article originally appeared on USA TODAY: Chiefs-Lions fight: JuJu Smith-Schuster hit by Brian Branch postgame