The Metro Transit Police are reviewing an incident Thursday night that started with an apparent misunderstanding over “horseplay” on a station platform and ended with a 13-year-old boy being handcuffed and spending the night in juvenile detention.

A Transit Police officer alleged the boy assaulted him; a witness says the officer used excessive force in handling the situation. Now the Transit Police Department’s Office of Professional Responsibility and Integrity is seeking “additional information” on the circumstances of the incident, Metro spokeswoman Sherri Ly said Sunday.

Cordell Mimms, a District musician, said he saw the boy get up from a bench at the Shaw-Howard University Metro station where Transit Police were questioning him.

When the boy “stood up momentarily,” a police officer “grabbed him by one of his arms, yanked him and pushed him down to the ground,” Mimms said. Two officers then forced the boy against the floor with their combined weight, he said.

“He’s crying and screaming and saying it hurts, and they keep exerting more force,” Mimms said. “It escalated very fast. It was jarring and shocking to see two grown men do that to a boy.”

Ly said police have opened an “administrative review” of the incident, but have “not reached any conclusions, as information is still being collected.” She said Metro is interested in speaking with any witnesses.

It all started, according to a Metro incident report, when a Transit Police officer riding a Green Line train said he saw “two male juveniles on the platform grabbing on to each other in a manner as if they were fighting.”

When the officer and a colleague stepped off the train, the juveniles “ran onto the train.” After the officers removed them and asked if they were fighting, the boys “stated they were just playing,” according to the report.

The 13-year-old gave police an incorrect name and repeatedly declined to give them a parent’s phone number. The officer said he needed it to inform them he had been stopped, and if he provided it “would send him on his way,” according to the report.

But things took a turn, the officer said, when the boy stood up from the bench.

In an incident report provided by Metro, one of the officers said the boy “stood up from the bench I had placed him on and when I stepped closer to him, he pushed me with his arm and said ‘back up from me.’ ”

The officer told the boy he was “under arrest for assaulting a police officer” and as the officer tried to handcuff the boy, “he started to pull away from me,” after which “I placed the respondent on the ground,” according to the report.

The boy put his hands in his pockets and refused to “give me his arms,” but two officers eventually handcuffed him and searched him, and the boy’s mother was contacted by cellphone, according to the report.

The boy complained of pain in his hands and back, and was taken to Children’s National Hospital, the report said. There, “the respondent started to become disorderly and failed to follow the instructions of the officers.” While officers were attempting to “secure the respondent to the bed,” the boy “started to kick his foot” and kicked one officer “in the center of his chest,” according to the incident report.

On Sunday, investigators with the Office of Professional Responsibility and Integrity interviewed a Howard University political science student, Donroy Ferdinand, who tweeted a video he took in the aftermath of the incident.

In a longer video taken by Ferdinand and reviewed by The Washington Post, the 13-year-old says: “You all don’t have a reason to put me in handcuffs.” The video began after the boy had already been handcuffed and was being walked out of the station to be taken to the hospital.

The boy goes on to say, “We told him we wasn’t fighting and that should have been the end of it. But then he’s talking about, he wants my information. I said, ‘No, I don’t have to do it. I didn’t commit a crime,’ ” the boy says.

An officer who had not been involved in the original incident appears to try to de-escalate the situation, asking the boy: “Why didn’t you tell him your information?”

The boy reiterates that he did not do so “because I did not commit a crime.”

The officer responds that: “it doesn’t matter. It doesn’t have to be a criminal offense. If you’re a student, and we have to make contact with you, we have to contact your parents.”’

The officer, also addressing onlookers who have gathered says: “He committed horse-playing, then refused to identify.” Asked by one what law was broken, the officer says: “It’s disorderly conduct.”

In the video, Ferdinand can be heard saying: “This is traumatizing. This is horrible.”

In an interview, Ferdinand said, “I really, really can’t imagine a situation where handcuffing him was, A, necessary, or, B, could de-escalate the situation. He was already upset and it only made him more upset.

“It was wild to me to see that slippery slope that turned horseplay into disorderly conduct into assault on an officer,” Ferdinand said, adding that the “ultimate takeaway from this is kids don’t belong in handcuffs.”

The boy’s mother said in an interview Sunday that she does not know all of the circumstances of the incident but that “from hearing what happened I feel like they were definitely too aggressive for his age and his size.” The Post is not naming the boy because he is a juvenile, nor his mother, to protect his identity.

The mother said that after her son spent the night in the city’s juvenile processing center, “I’m not for sure yet if they’re going to charge him or if he’s going to do a diversion program or what right now. They’re still gathering all the information.”

She said her son and the other boy who was involved are classmates and friends.