[Updated at 11:42 a.m.] At least 22 people are dead and 25 seriously injured in a forest fire in northern Israel, according to the country's ambulance service, which initially said 40 people were killed.

[Posted at 10:18 a.m.] Some 40 people have been killed in a raging fire near Haifa in northern Israel, Israeli ambulance service officials told CNN Thursday.

The fire broke out in the Carmel forest region. Police spokesman Micky Rosenfeld told CNN that some 3,000 square meters of trees were up in flames.

Rosenfeld said that a bus in the area overturned and emergency forces were trying to reach it. A spokesman for Israel's prison authority said the bus was carrying prison employees and that no prisoners were on board.

It is not clear how the fire started.

Firefighters were continuing to fight the blaze as authorities evacuated communities in the area.

The fire has been bolstered by strong winds and has torched tens of square kilometres of forest, cutting power and covering Haifa in smoke.

Inmates of the Damon prison were forced to evacuate and were sent to temporary jails nearby.

Police are investigating if the blaze started in an illegal dumping ground.