JERUSALEM, June 13 (Xinhua) -- A rocket fired by militants in the Gaza Strip hit a building in southern Israel on Thursday night amidst escalation between Israel and the Palestinian enclave.

Video footages and photos broadcast on local media TV channels showed that the rocket hit a multi-storey building in the town of Sderot, causing damage to a wall. Channel 12 TV news identified the building as belonging to a Jewish religious school.

Israel's Magen David Adom emergency medical service said no injuries were reported.

The military released a statement, saying that "one projectile was launched from the Gaza Strip into Israel," triggering sirens.

On Thursday before dawn, Israeli fighter jets struck a Hamas tunnel in the Gaza Strip, causing no injuries.

The strike followed a rocket launched by Gaza militants toward southern Israel overnight. Israel's Iron Dome air defense system intercepted the rocket and no damage or injuries were reported.

The rocket fire came hours after Israel announced it was imposing a naval blockade on Gaza "until further notice," citing helium-filled incendiary balloons that were launched into Israel's southern farmland.

The escalation was the first flare-up between Israel and Gaza since a cease-fire was announced in May after the worst violence between Israel and Hamas since the last full-fledged war in Gaza in 2014.

The Gaza Strip, home to about 2 million people, has been under an Israeli blockade since 2007. Under the blockade, Israel strictly limits the exit and entrance of people and goods, inflicting a humanitarian crisis on the territory.