A very frightening day for Israelis and Palestinians
Israel says Palestinian militants in Gaza have fired more than 460 rockets at it, and that its military has hit more than 130 militant targets in Gaza, in the heaviest fighting in nine months.
Six people were killed and 45 injured in Gaza, local medics say.
In Israel, several people were hurt rushing to shelters. Most rockets were intercepted or fell in open areas.
It comes a day after 15 Palestinians were killed in Israeli strikes on Gaza, including three Islamic Jihad leaders.
The BBC's Middle East correspondent Yolande Knell reflects on a very frightening day for Israelis and Palestinians.