Canadian officials are airlifting some 8,000 people who fled north of Fort McMurray - the city which has been devastated by a massive wildfire.

They also hope that the only motorway to the south will become safe on Friday to move the remaining 17,000 people, who are in danger of becoming trapped.

The entire city - more than 88,000 people - was evacuated three days ago. Most fled south but some went north.

The fire in the province of Alberta has grown to 850 sq km (328.2 sq miles).

Hundreds of firefighters are battling the blaze using helicopters and air tankers.

The fire, which covers an area almost the size of Calgary, Alberta's largest city, has slowed down and is now heading away from Fort McMurray.