Officials said that about 10 firefighting planes from Croatia, Cyprus, Greece and Italy, as well as Russia and Turkey, had either arrived in Israel or were on their way. The Palestinian Authority also said it would send some fire crews.
Netanyahu spoke on Thursday with Russian President Vladimir Putin, who agreed to send two massive firefighting planes that could drop water on the blazes. Local media reported that a supertanker firefighting plane would arrive from the United States in 24 hours.
Weather experts said the fires, which began in bush areas, had spread widely because of gusty winds following the dry summer months.
In Haifa, authorities removed residents from at least 10 neighbourhoods.
Although no fatalities were reported, damage was said to be widespread and a few hundred people were treated for smoke inhalation. Several large buildings were engulfed by the fires.
In addition to calling for help from abroad and directing all its firefighting forces to Haifa, the Israeli military deployed two search-and-rescue battalions to the area, and reservists from the Homefront Command were brought in to assist in evacuating civilians.
Some witnesses said the city, Israel's third-largest, resembled a "war zone."
As the fire continued to burn, Haifa residents remembered a deadly brush fire in 2010 in which 44 prison guards were burned alive on a bus as they attempted to reach and evacuate a prison. Israel's prison services said this time, too, that two prisons in the area would be emptied.
Yael Hamer, a resident of Haifa who was evacuated from her home Thursday, told journalists that the situation now was worse than the fire six years ago, when the fire was contained to the forests next to Haifa.
"Now it is residential areas where there are many private homes. It is near schools, gas stations, and there are a lot of cars that are stuck in traffic jams as people try to leave Haifa," Hamer said.
The first fire began Monday night near Neve Shalom, a small community halfway between Jerusalem and Tel Aviv, where Jews and Arabs live together. Just as that fire was brought under control, another erupted in Zichron Yaakov, a town just south of Haifa. Dozens of residents there were forced from their homes, and several houses were destroyed.
On Wednesday, a fire in the community of Nataf in the Jerusalem Hills damaged property. Israeli police said they had detained four Palestinians believed to have started the fire, although it was not clear whether it was on purpose or by negligence.
Throughout the night Wednesday, firefighters battled blazes in other areas, too. In one place, near the city of Modi'in, police were forced to close down the main highway to Jerusalem. Residents also were evacuated.
