The swim team still had hours to go on a dark Illinois highway when the bus pulled into a rest stop parking lot, and Jaylan Butler and his teammates filed out to relieve their tired bones.

Butler, then a 19-year-old freshman, took the opportunity for a selfie at a nearby sign — the perfect social media fodder to show parents and fans of Eastern Illinois University following their long journey home from a regional swim competition in South Dakota in February 2019.

What happened next, as recounted in a lawsuit, was a blur of flashing police lights and screaming officers who seemed to materialize from thin air before Butler could return to the bus. They ordered Butler to lie on the ground and tapped his forehead with a cold gun barrel.

“If you keep moving, I’m going to blow your f—ing head off,” an officer warned Butler, according to the lawsuit filed in U.S. District Court last month, which alleges that officers from three agencies violated the student’s civil rights when they mistakenly detained him while looking for someone else.

Butler, now 20, did not resist that night off a northern Illinois highway near East Moline, according to the suit. He had internalized his father’s lessons from “the talk” — the anguishing family advice that many black parents pass on to their children on how to navigate police stops, the suit says.

As soon as he saw the officers pull up, he put his hands in the air, let go of his cellphone and dropped to his knees, said Rachel Murphy, one of his attorneys at the American Civil Liberties Union of Illinois, which filed the suit.

“I imagine it was confusing and frightening,” Murphy told The Washington Post on Saturday. “He was just trying to get out alive.”

As many as six officers took part in the incident, which occurred after police mistook him for a suspect at large in the area. At least one officer jammed a knee into Butler’s neck, and at least one pressed onto his neck while he lay face down in the snow, Murphy said.

Todd Slingerland, the driver, said there was police activity a couple miles from the rest stop. Then a police cruiser rounded a hairpin turn and rushed toward the bus. “When I saw the cars screaming in, I knew something was going down that shouldn’t have gone down,” he told The Post on Saturday.

He watched the event unfold and tried to intervene. Slingerland, who said he is a 300-pound rugby player, was a few steps late trying to get between Butler and the officer. One racked a shotgun and yelled at the student.

“I would not have hesitated to tackle him,” he said.

The officers detained Butler for a prolonged period of time, searched him, placed him in the back of a squad car and threatened a charge of resisting arrest, then let him go without explanation after reviewing his ID, the suit says.

East Moline Police Chief Jeff Ramsey said officers in the area were searching for a suspect who shot at a vehicle and fled on foot near the parked bus, according to a statement released Saturday evening. They believed Butler may have been that suspect, who was later apprehended, he said.

Ramsey said the allegations Butler made were inconsistent with his initial review and said they are “without merit” but did not elaborate, citing pending litigation.

At the scene, Slingerland pressed one officer on the reason the event unfolded. They were looking for a black male and suspected the bus was being held hostage, Slingerland said he was told. It astounded him, he said, since they arrived in a deliberate manner and were aggressive to Butler after they learned he was a student and passenger on the bus.

“They were in search-and-destroy mode,” he said of the first two responding officers.

An officer each with the East Moline and Hampton police departments were sued, along with two deputies from the Rock Island Sheriff’s Office and two unidentified John Doe officers. The sheriff, Gerry Bustos, said his deputies were hunting for a fugitive and had a “brief interaction” with Butler. He said they arrived after Butler was detained and denied his allegations.

Slingerland pushed back against those assertions. “I can read, and the door that flew open had the word ‘sheriff’ on it,” he said.

Few details are known because the officers refused to provide written information at the scene, Murphy said. The officers did not give their names, specify the reason for the stop or hand Butler a receipt detailing the search, the suit alleges, which is required under two laws that collect statistics used to study potential bias in traffic stops.

Ramsey said the incident occurred in county jurisdiction and his department was assisting, but he declined to explain why his officer did not provide that documentation under the law.

Data from the statistics shows black drivers have been stopped at numbers disproportionate to their population in Illinois, the ACLU found.

Freedom of Information Act requests revealed the names of Rock Island Sheriff’s deputies Jack Asquini and Jason Pena; East Moline officer Travis Staes; and Hampton officer Ethan Bush as involved in the incident, Murphy said.

Hampton Police Chief Terry Engle referred questions to his legal counsel, who did not return a request for comment. Rock Island County State’s Attorney Dora Villarreal did not return a request for comment.

Butler is seeking unspecified damages in the suit, which is aiming at accountability of the officers involved, Murphy said.

The consequences have lingered for Butler, Murphy said. The incident made it difficult for him to focus on his business management studies, and he has sought counseling to help deal with the effects.

“He’s a really strong person,” she said. “He’s learning how to handle something traumatizing like this. It’s something he’s definitely going to be dealing with for a while.”

This story has been updated.

Alex Horton is a general assignment reporter for The Washington Post. He previously covered the military and national security for Stars and Stripes, and served in Iraq as an Army infantryman.