Kids seriously hurt in bear attack

A grizzly bear has attacked a school group on a walking trail in Canada, seriously injuring three children and one adult.

The attack happened on Thursday in the town of Bella Coola on the central coast of British Colombia, the country's westernmost province, and residents have been told to remain indoors until further notice.

Officers were still searching for the animal.

British Colombia's Conservation Officer Service said in a statement on Facebook the bear had yet to be captured despite teams working overnight.

The students and teachers had stopped along a trail near the river when the grizzly emerged from the forest and attacked, according to the statement.

Multiple teachers intervened, using bear spray and a bear banger to drive the animal away, it said.

Paramedics provided emergency medical treatment to four patients and transported them to hospital, the Provincial Health Services Authority told Reuters by email.

Two patients were critical condition and two in serious condition. 

A further seven people were cared for at the scene but did not require transportation to hospital.

"I want to thank the teachers for their heroism," British Colombia's Premier David Eby said at a news conference on Friday.

"I want to send my heart out to the parents and kids and loved ones and everyone who has been injured and is in hospital right now and I hope for their quick recovery."

The group was from the Acwsalcta School, run by the Indigenous Nuxalk Nation, which was closed on Friday.

The Nuxalk Nation Chief and Council said in a statement the attack had impacted children and so many loved ones.

"We remain in close contact with the families, and we understand that those who were injured are receiving the highest level of care," the statement said.