Palestinian militants in Gaza fired two rockets toward the Mediterranean sea on Saturday, causing an explosion off the shore of Tel Aviv, Israel's military said.

Police said there were no casualties or damage.

There was no immediate claim of responsibility from Gaza militants for the rocket firing or comment from Hamas, the armed group that rules the coastal Palestinian enclave.

Hamas has occasionally test fired rockets, launching them toward the sea.

The Hamas-affiliated Paltimes news website said, however, that the launch was not deliberate and was probably caused by a malfunction.

The Israel-Gaza frontier has been largely quiet since an 11-day war in May.

But on Wednesday, Palestinian militants in Gaza shot and lightly wounded an Israeli civilian near the security fence and Israel responded with tank fire targeting multiple Hamas sites in the first exchange of fire in months, wounding three Palestinians.

Apart from a single incident in September, there has been no cross-border rocket fire since a cease-fire ended an 11-day war between Israel and Hamas in May.

In a statement, the Israeli army said the rockets fell off the coast of the Tel Aviv Metropolitan Area. “According to protocol, no sirens were sounded and no interception took place,” it added.

Witnesses in Gaza said they woke up to the sound of outgoing missiles around 7 a.m. and pictures circulated on social media showed whiffs of white smoke from the launching area.

The cease-fire, brokered by Egypt and other mediators, has been fragile.

The Hamas group says Israel did not take serious steps to ease the blockade it imposed on Gaza with Egypt’s help when the militant group seized control of the coastal enclave in 2007.

Tension are also high as other groups like the smaller but more hard-line Islamic Jihad threaten military escalation if Israel doesn’t end the administrative detention of a Palestinian prisoner who has been on a hunger strike for over 130 days.