Ontario's police watchdog is investigating after a Somali-Canadian Ottawa man with a "mental capacity issue" was taken to hospital in critical condition Sunday following an attempted arrest west of downtown.

Abdirahman Abdi, 37, suffered 'medical distress' during a confrontation with police on Sunday and was taken to The Ottawa Hospital's Civic campus, where he was listed in critical condition on Monday. (Image supplied by family) Around 9:30 a.m., officers with the Ottawa Police Service were called to Wellington Street West and Fairmont Avenue for reports of groping.

Police located a 37-year-old man, and shortly afterwards there was a "confrontation" outside a building at 55 Hilda St., a few blocks away, said Special Investigations Unit spokesman Jason Gennaro in a statement.

Sources told CBC News the officers used pepper spray and a baton during the confrontation.

The man suffered "medical distress" during the confrontation and was taken to The Ottawa Hospital's Civic Campus, where as of Monday morning he was still listed in critical condition.

Nimao Ali gives a statement on Abdirahaman Abdi's condition. Family has asked her to speak on their behalf <a href="https://twitter.com/hashtag/ottnews?src=hash">#ottnews</a> <a href="https://t.co/TBBHjpxYLi">pic.twitter.com/TBBHjpxYLi</a> —@idilmussa

Abdirizaq Abdi told CBC News Sunday that he was on the eighth floor of his building when a neighbour yelled that police were arresting his brother Abdirahman.

"I heard the screaming, and then I come out and I see my brother lying down, police hitting so badly. Like, I've never seen something like that in my life," Abdi said.

"All of them, they were on top of him. He was under [them] ... they were hitting like [he was] an enemy. I've never seen something like that."

His family initially thought he had died during the attempted arrest.

Abdirizaq Abdi speaks to a reporter after his brother was hospitalized following an arrest Sunday in Ottawa's Hintonburg neighbourhood.

Moved to Canada from Somalia

Abdi said his brother had been "sick" and that he rarely spoke to other people. The family immigrated to Canada from Somalia, he said.

"I live in a country that there's no government and I've never seen something like this," he said. "I only live eight years [here] and this happen for nothing. And I wasn't expecting like this stuff to happen."

City Coun. Jeff Leiper, who represents the area, met with the family on Sunday. He said the man who was arrested was a common face in the neighbourhood and suffered from "a mental capacity issue."

Heading home now from Hilda, waiting to hear more from the family at the hospital. All we can do is wait. —@JLeiper

"What is clear, at least to me, is that there is a mental capacity issue that was at play here," Leiper said. "Residents and the family are suggesting that that was part of whatever transpired here this morning."

'Initial discomfort'

Leiper also said there was "initial discomfort" among the residents of the building where Abdirahman Abdi was arrested, many of whom are new Canadians, about whether the arrest would be looked into.

"When I spoke to them about the role that the SIU plays, and why it's different from Ottawa police, that seemed to reassure them that this incident will be investigated seriously," he said.

Members of the Ottawa Community Immigrant Services Organization would also likely be talking to residents about the incident and what happens next, Leiper added.

Police tape blocks off a stretch of Hilda Street in Ottawa on July 24, 2016. The province's Special Investigations Unit is investigating after Abdirahman Abdi died from his injuries after police tried to arrest him Sunday. (Catharine Tunney/CBC)

The Ottawa Police Service declined to comment, saying only that the SIU is handling the investigation.

2 officers directly involved

Five investigators and one forensic investigator have been assigned to investigate this incident, said the SIU. Two Ottawa police officers have been identified as subject officers in the confrontation and five others are being interviewed as witnesses.

"A subject officer is a police officer whose conduct may have caused the serious injury that's under investigation. ... Essentially, they can be considered similar to a suspect in a criminal investigation, so they also have the same rights as a citizen under the Charter of Rights and Freedoms in terms of protection against self incrimination," said Gennaro of the SIU.

"So we invite subject officers to submit to an interview and present themselves to the SIU, but they do not need to do so."

The agency is urging any witnesses to contact the lead investigator at 1-800-787-8529.

Ontario's SIU investigates whenever there is a death, serious injury or allegation of sexual assault involving police in the province.