The province's Special Investigations Unit is probing a shooting at the Queen subway station in downtown Toronto that sent a young man to hospital and holiday shoppers running for their lives.

An 18-year-old man was rushed to St. Michael's Hospital after being shot at around 8 p.m. on Friday. He remains there in stable condition.

The SIU’s Carm Piro said a total of nine officers responded to reports of a "suspicious person" on a subway train.

He said the person had a weapon, but wouldn't elaborate.

Four officers are believed to have fired their guns, according to the SIU.

Some witnesses reported hearing as many as 15 shots, sending terrified commuters streaming out of the subway station, which connects to the south end of the busy Eaton Centre shopping mall.

"It was like people panicking, screaming and then people saying 'get off ' … some people were crying," witness Kevin Chan told reporters.

“Obviously it's like a nightmare. It's so scary,” said Jane Whitbread, who was in the mall at the time. “There's like so many people … it's terrifying.”

The Yonge Street subway line remained shutdown through Saturday morning from Bloor Street to Union Station, but reopened by early afternoon.

The SIU has assigned nine investigators and four forensic experts to investigate the incident.

The SIU is called in whenever police officers are involved in incidents in which someone has been seriously injured, dies or alleges sexual assault.