The cause of the worst forest fire in Israel's history is probably negligence rather than arson, authorities said, as firefighters from around the world battled the blaze whipping through northern pine forests towards the Mediterranean.
A spokesman for Israel's police would not go into detail about the kind of negligence or explain why authorities were now leaning away from earlier suspicions of arson until further investigations have been carried out.
By midday on Saturday, firefighters had still not brought the blaze under control, said the spokesman, Micky Rosenfeld.
The fires burning north of the city of Haifa began on Thursday, killing 41 people - most of them prison guards whose bus was engulfed by flames while they were on their way to evacuate a jail. The fires have forced the evacuation of 17,000 people.
The blaze was burning through the Carmel Forest, a prized area of woodland, sending a dark cloud of ash over much of northern Israel.
Israel's small firefighting force was overwhelmed and the country sent out an unprecedented call for international help. Aircraft from Turkey, Greece, Cyprus and Britain were dumping sea water and flame retardant over the area.
Two more communities were evacuated. Some residents refused to go and pleaded with firefighters for help save their homes. One woman in the small artist community of Ein Hod desperately tried to protect her home from the encroaching flames with only a garden hose.
Residents of a nearby farming village were also ordered to leave.
Above them, small planes swooped and dumped orange fire retardant and sea water over tracts of dry pines which were lit up by flames.
US planes laden with equipment were expected to land later, alongside planes sent from New York City's firefighting department, a military official said.