JERUSALEM -- Palestinian militants fired a rocket into southern Israel early Saturday, shattering a two-month lull in violence at the Gaza-Israel border in contrast to soaring tensions in the occupied West Bank.
The Israeli military said aerial defense systems intercepted the projectile, which activated warning sirens in the southern coastal city of Ashkelon. There were no reports of casualties.
Hours later, Israeli aircraft carried out a series of airstrikes on four military sites for Hamas, the militant group that rules Gaza. Videos on social media showed plumes of smoke and fire rising from the targeted camps in central and northern Gaza Strip and eastern Gaza City.
No Palestinian group claimed responsibility for the rocket fire but the Israeli military blamed Hamas.
An Israeli military raid in the West Bank early Friday, in which three Palestinian militants were killed and eight wounded, could have triggered the rocket attack from Gaza.
Also on Friday, an Israeli observation balloon crashed and fell in northern Gaza Strip. The Israeli military said it was investigating the incident but clarified the balloon was not downed by Palestinian militants.
The Israeli military has been carrying out near-daily raids in the occupied West Bank since a string of attacks earlier this year killed 19 people in Israel. Many of the arrest raids have been launched in and around Jenin, the hometown of several of the attackers.