Israeli media are describing it as the biggest forest fire in the country’s history.
An estimated 40 people have been killed, many of them prison guards trapped in a bus as they tried to flee the flames.
Several people are reported injured in the fire near Haifa in the north of the country, which follows a long period of drought.
Israel has called on several European countries to send aircraft to help battle the blaze.
“The fire is enormous, it is very hard to bring under control, if we didn’t have one plane at our disposal it would be very difficult,” said one fireman.
At least two thousand people have been evacuated from areas around the Carmel mountains where the fire has been raging.
There are conflicting reports about the circumstances surrounding the prison guards who died.
Some 500 prisoners – including, it is thought, Palestinians – were moved to safety as the fire spread.
One official said the guards from all over Israel were attending a course at the jail and were trapped as they tried to escape.
But other reports said they were heading towards the prison to help with the evacuation.