Bills RB Karlos Williams leaves with shoulder injury

KANSAS CITY, Mo. -- Buffalo Bills running back Karlos Williams left Sunday's game against the Kansas City Chiefs in the first quarter after suffering a shoulder injury.

The team said his return to the game was questionable. Williams is Buffalo's No. 2 running back behind starter LeSean McCoy.

Buffalo rookie cornerback Ronald Darby left the game with a possible concussion.

After helping to tackle Kansas City running back Spencer Ware, Darby appeared disoriented returning to the huddle. Line judge Tom Stephan stopped play on the field and walked him halfway to the Bills bench.

The team announced Darby was undergoing tests in the NFL concussion protocol.

Chiefs outside linebacker Justin Houston left due to a left leg injury with just under four minutes to play in the first quarter.

On the Kansas City sidelines, doctors were examining his lower left leg. One of his teammates, safety Ron Parker, took Houston's legs out from under him at the end of a play, leaving the linebacker withering on the field in pain. Eventually, Houston was taken to the locker room. Frank Zombo replaced Houston at left outside linebacker in the Chiefs' defense.

Chiefs left guard Jeff Allen had to be helped off the field midway through the second quarter with a left ankle injury. He was questionable to return.

Allen was injured on a 3-yard touchdown run by teammate Spencer Ware. He limped off the field with help from doctors, unable to put any pressure on his left leg.

In the preseason's opening game, Allen suffered a torn MCL in his left knee and missed the rest of training camp and the preseason schedule.

Buffalo starting outside linebacker Nigel Bradham suffered an ankle injury in the third quarter. The Bills listed him as questionable to return.

Bills defensive end Alex Carrington was injured on the final play of the third quarter in the game against the Chiefs. It was reported as a right knee injury.

Carrington was taken off the field on a cart. He opened the game for injured starter Mario Williams.

Chiefs starting center Mitch Morse was pulled from the game late in the third quarter because of a possible concussion.

The first-year center had made every snap on the season for the Chiefs offense. He was replaced by guard Zach Fulton, who moved over from left guard. Fulton was playing in place of the injured starter Jeff Allen (ankle).