Toronto police have agreed to review an incident during which two Toronto Transit Commission enforcement officers were filmed fighting with two men at Toronto's Union Station.

A TTC statement issued Wednesday said Toronto police Chief Bill Blair — responding to a request from TTC boss Andy Byford — has asked his professional standards unit to lead the investigation.

Speaking at a news conference Wednesday, Byford said the two TTC enforcement officers involved will perform administrative duties while police conduct their investigation.

Byford said he was "extremely concerned" upon learning about the videos on Tuesday, but said the investigation is needed to fully understand the context of what happened.

"We don't want members of our staff getting into a fight," he said. "But it's important that we understand the full picture."

​The six-minute video, which was posted on both YouTube earlier this month and started spreading quickly online Tuesday night, shows an incident from the evening of Jan. 29, as the downtown subway station fills up with fans leaving a Leafs game at the Air Canada Centre.

Everyone involved appears to struggle or throw a punch at some point. However, during one moment where the situation appears to be calming down, one of the transit enforcement officers punches one of the men hard in the face twice.

Later, the same officer throws a flurry of punches at the man as he's held against a wall.

Two men were arrested by police and charged with assault. They were identified by police Wednesday as:

Jamie Gillman, 33.

Russell Gillman, 63.

Both were charged with assault and uttering death threats.

It's not known what sparked the fracas, but Byford said Wednesday it wasn't related to a fare dispute.

He said investigators will look at social media material and also CCTV footage, which he said has been handed over to police.

The TTC employs two levels of enforcement officers: transit enforcement officers and special constables. At the time of this incident, both men were TEOs. One of the men has since become a special constable, Byford said.

Special constables undergo 54 days of training to what Byford described as a "police standard." Eight of those training days are dedicated to de-escalation techniques.

Byford said the two officers submitted reports after the incident back in January as they are required to do. No further action was taken internally because the two men involved were charged by police and a complaint was not filed. To date, the TTC has received no public complaint about the incident, Byford said.

"It's obviously very disturbing and so I'm really shocked. The first time I watched the video was just moments ago, but I don't know the full story," said TTC chair Coun. Josh Colle.

"We're supposed to de-escalate and in certain situations then you call in Toronto police," he said.

Mayor John Tory said Wednesday that he believes Byford has acted appropriately by having police review the incident.

"I'd be concerned if they were trying to cover something up. But I didn't see any evidence of that," he said.

At the end of the video, three police officers arrive and quickly put one of the men in cuffs.

Fight caught on camera

The video begins with one TTC officer already grappling with a middle-aged man as a fare collector and commuters look on.

"Turn around, you're under arrest," the TTC officer says. "What don't you understand?"

The middle-aged man and his son struggle with the officer, while several commuters try to intervene. But, after the camera briefly moves away from the grappling men, punches start flying, and the younger man can be seen hitting the TTC officer multiple times.

A second TTC officer arrives and joins the fracas.

As blows fly, the fare collector tries to hold one of the men against a wall.

At one point, one of the men can be heard saying, "I didn't do anything." His mouth appeared bloodied.

"I paid my fare … what the f--k is going on here?" he says.

Moments after the last barrage of punches are thrown, police officers arrive and handcuff the younger man. As the officers lift him to his feet, one officer asks if he's OK and the man appears to calm down immediately before the video ends.