JERUSALEM — Palestinian militants barraged Israel with nearly 150 rockets on Thursday, killing three people and striking the southern outskirts of Tel Aviv as Israel pressed a punishing campaign of airstrikes on militant targets across the Gaza Strip.

As nightfall approached, the fighting showed no signs of slowing, and the rocket attack on the city of Rishon Lezion, by far the deepest target reached by Gaza militants so far, raised the likelihood of an even tougher Israeli response.