A grizzly bear is on the loose after attacking a school group in Canada, leaving 11 people injured, two critically.

The incident happened on Thursday afternoon on a walking trail in the town of Bella Coola, in the province of British Columbia.

Residents have been warned to remain indoors while armed officers try to track down the animal.

A male teacher “got the whole brunt of it” and some children were hit with bear spray as the adults tried to fend off the animal, Veronica Schooner, a parent, told the Canadian Press.

Ms Schooner said her 10-year-old son was part of the school group, though he was not attacked.

“He said that bear ran so close to him, but it was going after somebody else,” she said, adding that “he even felt its fur”.

British Columbia Emergency Health Services said two people were critically injured, two more were seriously hurt, and seven others were treated at the scene, reports the Canadian Press.

The group were from Acwsalcta School, which is run by the indigenous Nuxalk Nation, in the town located 700km (435 miles) north-west of Vancouver.

“Officers are armed” the Nation wrote on Facebook. “Remain indoors and off the highway.”

“It’s hard to know what to say during this very difficult time. We are so grateful for our team and our students.”

The Nation’s officials have temporarily shut the school, offering counselling services. (BBC)