The army called up reservists and hospitals in the Mediterranean port city declared an emergency for fear of a repetition of a 2010 blaze that killed 44 people -- the deadliest in Israeli history.
"We evacuated three neighbourhoods and there are people who are stuck," fire department spokesman Kayed Daher said.
"The fire is still burning and the flames are approaching a gas station."
Flames up to 10 metres (more than 30 feet) high were threatening several multi-storey tower blocks in one Haifa suburb, an AFP photographer at the scene reported.
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In the affluent Carmel neighbourhood on the heights above the city, residents spoke of a desperate rush to get elderly residents out.
"The fire is out of control and is spreading from one house to the other," the neighbourhood's rescue services chief, Naftali Rottenberg, told public radio.
"The fire is advancing 20-30 metres (yards) in a few minutes.
"Sometimes we are taking residents out against their will."
The scale of the blaze prompted a growing list of countries to send help, including firefighting aircraft. They included Croatia, Cyprus, Greece, Italy, Russia and Turkey.
Israel has been hit by a spate of bushfires in recent days that officials attribute to an unusually dry autumn and strong winds.
Fires were raging in two areas on the outskirts of Jerusalem as well as near the Jewish settlement of Talmon in the occupied West Bank, police said.
Internal Security Minister Gilad Erdan told army radio that around half of the recent fires had been started deliberately.
Education Minister Naftali Bennett of the far-right Jewish Home party appeared to blame the arson on members the country's Arab minority.