LAS VEGAS -- Raiders quarterback Gardner Minshew suffered a season-ending broken collarbone late in Las Vegas' 29-19 loss to the Denver Broncos on Sunday, a source confirmed to ESPN's Adam Schefter.

Minshew, signed in March to a two-year, $25 million contract with $15 million guaranteed, was injured on a fourth-quarter sack by Broncos linebacker Cody Barton.

Minshew landed awkwardly on his left shoulder and appeared to be fighting back tears as he exited the field holding his left arm in a curled position. He went straight to the locker room with a trainer.

"It doesn't look good," Raiders coach Antonio Pierce said after Las Vegas dropped its seventh straight game to fall to 2-9.

With Minshew out, the Raiders are left at quarterback with Desmond Ridder, signed off the Arizona Cardinals practice squad Oct. 22; Aidan O'Connell, now eligible to come off injured reserve after suffering a broken thumb on his right (passing) hand Oct. 20; and practice squad member Carter Bradley.

Las Vegas, though, has a short week, with a game Friday at the two-time defending Super Bowl champion Kansas City Chiefs.

"We're going to need somebody, right?" Pierce said. "We're running out of quarterbacks, too, now, so we'll see what happens [Monday]. But obviously, it looks like [O'Connell is] getting better. He threw a little bit in practice this week.

"Obviously, we've got a short week -- play on Friday, travel on Thursday -- so we have to make that decision very quickly."

O'Connell was not available to the media after the loss to Denver, but Ridder said he will be ready for the Chiefs should his number be called.

"I've been here almost a month and how I feel comfortable with the offense, I'm ready to go," said Ridder, who completed 5 of 10 passes for 64 yards against the Broncos but lost a fumble on a sack on his first series. "So whatever that situation may be, it's not up to me -- it's up to the higher power. But I'm ready for any situation there may be."

For Minshew, it marks the end of a frustrating season after he won a close training camp battle with O'Connell.

After a slow start, one that included a 100-yard pick-six by Patrick Surtain at Denver, Minshew was benched in favor of O'Connell in Week 6. O'Connell was then injured in his second start and Minshew again became the starter.

In 10 games (nine starts) this season, Minshew passed for 2,013 yards while completing 66.3% of his attempts. He had nine touchdown passes but also had a career-high 10 interceptions and fumbled five times, losing three. His QBR of 39.1 entering Sunday was a career low.

Since the Minshew pick-six at Denver, the Raiders have been outscored by a combined 214-118 and are tied with the Jacksonville Jaguars and New York Giants for the worst record in the NFL.

NFL Network first reported the severity of Minshew's injury.