GAZA CITY, Gaza Strip (AP) — Israel’s military fired on Hamas installations in Gaza after a rocket launched from the territory exploded inside Israel on Monday, with no reports of casualties on either side.

Hamas, the Islamic militant group that rules Gaza, has largely adhered to a cease-fire that ended a 50-day war with Israel in 2014, but other militant groups occasionally fire rockets or mortar rounds over the frontier. Israel holds Hamas responsible for all incoming fire.

Sirens wailed in parts of southern Israel warning of incoming rockets early Monday. The military said one exploded in an open field. Soon after the attack, it said a tank fired at a Hamas position near the frontier.

Hours later, Gaza residents said Israeli airstrikes targeted two separate Hamas-run militant training sites. The residents asked not to be identified for security reasons. The Israeli military had no immediate comment.

There was no immediate claim of responsibility in Gaza for the rocket attack. Jihadists who support the Islamic State group have taken responsibility for similar attacks in the past.