Canadian Prime Minister Justin Trudeau is condemning the pepper spraying of a group of Syrian refugees in Vancouver, which police are treating as a hate crime.

Police said the incident happened Friday night when people had gathered outside the Muslim Association of Canada Center during a "welcome night" for newly arrived Syrian refugees. A man wearing a white hoodie apparently rode by on a bicycle and sprayed 15 to 30 people, police said.

"This isn't who we are — and doesn't reflect the warm welcome Canadians have offered," Trudeau posted on Twitter on Saturday.

Nawal Addo, a 16-year-old of Syrian background who grew up in Canada, said she was standing outside with some refugees who were waiting for a bus when everyone began to cough and feel their eyes burning.

"We saw people coming out from the building and they were in worse condition than us," she said. "Their eyes were really puffed up. They weren't able to open their eyes."

She said it appeared the fumes had gotten inside the entrance, where it affected people more powerfully in the enclosed space. Some were children, including a girl who was about 2, Addo said.

Some people were vomiting and a few had to be taken away by ambulance, including the toddler, she said.

Addo said she didn't see the man on the bicycle. "There was only one witness, and he didn't even see his face," she said.

Vancouver Police Sgt. Randy Fincham said no one has been arrested.

"Although the motive for the pepper spraying is unknown at this time, investigators are treating it as a hate-motivated crime, until determined otherwise," he said in a news release.

B.C. Premier Christy Clark, Vancouver Mayor Gregor Robertson and federal Immigration Minister John McCallum also expressed outrage at the attack.

"This attack in no way represents their new home," McCallum said in a statement.

Canada's government has committed to welcoming 25,000 Syrian refugees by the end of next month. Thousands have already arrived.