Britt Reid, Chiefs assistant coach and son of Andy Reid, involved in crash that seriously injured child

Britt Reid is being investigated for "impairment," police said.

Britt Reid, an assistant coach for the Kansas City Chiefs and the son of head coach Andy Reid, was involved in a serious crash Thursday night, according to police. Reid is being investigated for "impairment," Kansas City police said.

Reid suffered non-life-threatening injuries, but two children in a car involved in the crash were seriously injured, including one with life-threatening injuries.

The 35-year-old is a linebackers coach for the Chiefs, who played in the Super Bowl against the Tampa Bay Buccaneers.

Head coach Andy Reid issued a statement in a postgame press conference Sunday night, saying, "My heart goes out to all those that were involved in the accident – in particular the family with the little girl who is fighting for her life."

"And listen, it’s a tough situation -- I can’t comment on it any more than what I am here -- so the questions that you have I’m gonna have to turn those down at this time," he continued. "But just from a human standpoint, my heart bleeds for everybody involved in that."

In the Chiefs' initial statement, the team said: "The organization has been made aware of a multi-vehicle accident involving Outside Linebackers Coach, Britt Reid. We are in the process of gathering information, and we will have no further comment at this time. Our thoughts and prayers are with everyone involved."

The accident took place Thursday night at about 9 p.m. near the Chiefs' practice facility at the Truman Sports Complex, according to police.

Reid hit a car that had run out of gas on the side of the road, causing a chain reaction that hit another car belonging to relatives assisting the stranded car, according to police. A 5-year-old in the second car suffered life-threatening injuries, while a 4-year-old in that car suffered non-life-threatening injuries, police said. Both were transported to the hospital. The 5-year-old remained in critical condition on Saturday, police said.

The driver of the car Reid hit first and two adults in the second car were not injured.

According to a warrant obtained by ESPN, Reid admitted to being the driver of the Ram Laramie that caused the accident. An officer who arrived at the scene of the crash said he could smell a "moderate odor" of alcohol on Reid, and that his eyes were bloodshot. When asked if he had been drinking, Reid allegedly said he had two to three drinks and had also taken Adderall, according to the warrant.

After complaining of stomach pain, Reid was transported to a local hospital, where he was being observed for "clues of impairment," according to the warrant.

The warrant also notes that Reid has "multiple prior DUI contacts."

The Chiefs had been in Kansas City due to COVID-19 protocols.

Reid did not travel to the Super Bowl, a source told ESPN's Dianna Russini, as he was still hospitalized. He could be hospitalized for days due to his injuries, the source added.

The Kansas City Police Department confirmed to ABC News that if there are charges in this case, they will not be filed until after the Super Bowl, because a normal investigation of this nature would take at least a few weeks.

Since 2013, Reid has worked alongside his father, who has coached in the NFL since 1992 and taken the Eagles and Chiefs to the Super Bowl. Andy Reid won his first title with Kansas City last year.

Britt Reid pleaded guilty to simple assault and flashing a gun at another driver in a road rage incident in 2007, according to Montgomery County, Pennsylvania, court records, and served prison time. While in prison, he also pleaded guilty to a charge of driving under the influence of a controlled substance from a separate incident, court records show.

He was twice given tickets for speeding while working for the Chiefs -- on Aug. 19, 2014 and Aug. 9, 2018 -- according to court records. He paid both fines.

ABC News' Nick Cirone and Matt Foster contributed to this report.