Patrick Mahomes is known to keep his composure. The Kansas City Chiefs quarterback has reached his breaking point.

Mahomes was shown screaming at referees and slamming his helmet on the CBS broadcast after the Chiefs had the lead wiped away by a penalty and lost 20-17 at home to the Buffalo Bills.

It looked like the Chiefs scored the go-ahead touchdown with 1:12 remaining. Mahomes threw a deep completion to Travis Kelce, who was being chased by three Bills defenders when he turned and threw a backward pass to Kadarius Toney. Toney ran untouched into the end zone for a play that covered 49 yards but the touchdown was nullified becasue Toney was offsides.

Kansas City's drive ended with a whimper as Mahomes threw three consecutive incompletions to turn the ball over on downs.

Mahomes was upset at the penalty against Toney. Fans on social media opined Mahomes was incensed because Bills defensive end Von Miller appeared to be offsides two plays after the Toney penalty and it wasn't called by officials.

He seemed to be yelling "Offensive offsides? That's terrible, man" on a close-up video by CBS.

"It's obviously tough to swallow, not only for me but for football in general, to take away greatness like that," Mahomes said. "Who knows if we win, but I know as fans you want to see the guys on the field decide the game ... They're human, man. They make mistakes. Every week we're talking about something.

"Another game, we're talking about the refs. It's not what we want for the NFL or for football," Mahomes told reporters after the game. He said he asked three referees for an explanation but wasn't given one.

"Very disappointed that it ended the way it did. Normally, I get a warning before something like that happens in a big game," Kansas City head coach Andy Reid said. "A bit embarrassing in the National Football league for that to take place."

Kansas City's season has been hampered by untimely drops and penalties by its wide receiver corps. Last week, a controversial no-call on an apparent defensive pass interference in the final minute ended their hopes at tying the game in a 27-19 loss to the Green Bay Packers on Sunday Night Football.

This article originally appeared on Rochester Democrat and Chronicle: Patrick Mahomes screams at refs, slams helmet after Chiefs loss to Bills