Mexico's Cesar Montes - for kicking Arsenal's Folarin Balogun - and Gerardo Arteaga were dismissed along with US duo Weston McKennie and Sergino Dest.

The match was paused near the end because of homophobic chanting.

Pulisic put his side 2-0 up in Las Vegas before Montes was dismissed in the 69th minute for a wild tackle on forward Balogun, who was making his US debut after switching allegiance from England.

McKennie, who was on loan at Leeds United from Juventus last season, was sent-off for his part in the scuffle.

Pepi added a third for the US in the 78th minute and both sides had another player red carded when Arteaga and Dest were sent-off following another mass brawl.

Drinks were also thrown from the stands while fans were warned in stadium announcements that the game could be suspended because of the homophobic chanting.

The referee blew for full-time with about half of the 12 minutes of scheduled added time still to play.

"It's a great scoreline for us, it's a big win and we're into the finals," Pulisic said. "But the game didn't need to turn into all the madness that it did.

"They really need to control the game much more. It's sad. And now we're missing two good players just because everyone's losing their heads.

"I'm a little bit upset but at the end of the day we're in the final."

BJ Callaghan was in charge of the US team for the game but there are reports Gregg Berhalter could return to the post.

An independent investigation - launched after he admitted in a statement co-signed by his wife Rosalind that he kicked her during an argument in 1992 - decided there is "no legal impediment to employing" the coach again.

The US will play Canada in the Concacaf Nations League final on Monday after they beat Panama 2-0 thanks to goals from Jonathan David and Alphonso Davies.