Kansas City, Mo. ? The season appears to be over for Pro Bowl running back Jamaal Charles.

Might be for the Kansas Chiefs, too.

Jay Cutler led Chicago to a pair of fourth-quarter touchdowns Sunday, the second an alert toss to Matt Forte with 18 seconds remaining, giving the Bears an 18-17 comeback victory after the Chiefs’ star running back sustained what appears to be a torn ACL in his right knee.

The second heartbreaking home loss of the season was also the fourth straight defeat for the Chiefs (1-4), whose playoff hopes are already fading before the midway point of the season.

“What’s the truth? I think that’s the important part,” Chiefs coach Andy Reid said. “You’re put in a situation like this, you have to make plays. We didn’t do that.”

The Chiefs were leading 17-3 in the third quarter when Charles went down while trying to make a cut. The preliminary diagnosis was a torn ligament, and he’ll have an MRI today.

With him out of the game, the Bears (2-3) quickly seized the momentum.

After Robbie Gould’s second field goal got them going, Cutler led an 88-yard drive that he capped with a 22-yard pass to Marquess Wilson with 3:05 left. The two-point conversion came up short, but the Bears defense responded by forcing a quick three-and-out.

With help from a pass interference call on Chiefs rookie Marcus Peters, the Bears quickly moved downfield. That’s when Cutler took a snap from the shotgun, dropped the ball, picked it up and spotted Forte running past safety Husain Abdullah in the end zone for the go-ahead score.

“There’s a lot of pride in that offensive huddle,” Cutler said. “Those guys fought hard.”

The Chiefs’ fourth-quarter collapse was reminiscent of their home opener, when AFC West rival Denver scored two touchdowns in the final 2:27 for a 31-24 victory last month.

Making this one even worse was the injury to Charles, who was starting to get into a rhythm went he went down deep in Chicago territory. He immediately grabbed his right knee — Charles tore the ACL in his left knee four years ago — and was helped straight to the locker room.

“Charles is one of the tougher guys in the NFL, so I’m thinking he’s going to get up,” backup running back Charcandrick West said. “It brought tears to my eyes. It’s heartbreaking.”

It became even more heartbreaking when Chiefs’ drive stalled, and Cairo Santos had his field-goal attempt blocked. The missed points wound up looming large in a game Kansas City could look back on all season for its missed opportunities.

“We had so many opportunities to win this game,” wide receiver Jeremy Maclin said, “and we blew it. We don’t have anybody to blame but ourselves.”

Until Charles went down, everything was going splendidly for the Chiefs, who had jumped out to a comfortable lead thanks to a pair of surprising touchdowns.

The first occurred on the third series of the game, when Cutler was sacked in the end zone by Jaye Howard and Allen Bailey. Cutler lost the ball before hitting the turf, and rookie linebacker Ramik Wilson jumped on it for a touchdown in his first NFL start.

The Chiefs’ second TD came when Alex Smith connected with DeAnthony Thomas with a 14-yard pitch-and-catch midway through the second quarter. Why so surprising? It was the second scoring reception by a Kansas City wide receiver since December 2013.

Meanwhile, the Bears were struggling through their own injury problems.

Wide receivers Alshon Jeffery and Eddie Royal were both out, along with three of the Bears’ starting offensive linemen. The result was a tough afternoon for Cutler until the final minutes, when he made the plays that mattered most.

“It’s a tribute to everybody in that locker room,” Bears coach John Fox said. “We’ve practically run out of room in that training room. It’s what’s cool about it.”

Notes: Smith was 16 of 30 for 181 yards without an interception, but was sacked three times. He’s been sacked 22 times already this season. … Fox improved to 8-1 against Kansas City. Most of those wins came with Denver. … Cutler needs three TD passes to surpass Sid Luckman (137) for most in franchise history. … West ran for 31 yards once Charles left the game.