Palestinian militants in the Gaza Strip unexpectedly fired dozens of rockets at targets in Israel on Saturday morning.
Warning sirens wailed in various cities across the country, the army said. Rocket alarms were also heard in Tel Aviv.
The military called on residents of the southern and central parts of the country to stay in protected areas.
Medics reported injuries in the rocket attacks in the areas of Ashkelon, Gedera and Javne. A 70-year-old woman was critically injured in a direct hit in a building near Gedera, said the Magen David Adom rescue service.
Israel is currently celebrating the Jewish festival of Simchat Torah (Joy of the Torah). Prime Minister Benjamin Netanyahu wanted to hold security consultations with representatives of the Defense Ministry and the army later in the day.
A firefighter puts out a house fire
The massive attack from the Gaza Strip came as a surprise. However, the situation, particularly in the occupied West Bank, had recently worsened again. Four Palestinians have been killed there since Thursday in their own attacks or in confrontations with the army.
The security situation in Israel and the West Bank is tense. Since the beginning of the year, 27 Israelis, one Ukrainian and one Italian have been killed in attacks.