Palestinians fired several rockets into southern Israel from the Gaza Strip early Thursday as Israeli aircraft hit Gaza militant sites soon after an earlier rocket strike that was the second such attack this week.

The cross-border Gaza violence was an extension of Israeli-Palestinian tensions that have been boiling in Jerusalem.

The Israeli military said four rockets were fired from Gaza early Thursday and were intercepted by air defenses. Late Wednesday, a rocket was fired from Gaza, triggering Israeli airstrikes.

There were no immediate reports of casualties or damage, and no one claimed the rocket strikes. Israel holds the Hamas militant group that rules Gaza responsible for all rocket fire and typically responds with airstrikes within hours.

Early Thursday, Israeli warplanes conducted a series of airstrikes at a Hamas military site in the central Gaza Strip, local media reported. Social media posts by activists showed smoke billowing in the air. The Israeli military said the airstrikes were aimed at a militant site and an entrance of a tunnel leading to an underground complex holding “raw chemicals” to make rockets.

Hamas had earlier issued vague threats over a planned march through Jerusalem by Israeli ultra-nationalists. But Israeli police blocked roads and prevented the marchers from reaching dense Palestinian neighborhoods in and around the Old City, after a similar event nearly a year ago helped trigger an Israel-Gaza war.

Police used parked trucks and barricades just outside the walls of the Old City to close the main road leading down to Damascus Gate, the epicenter of last year’s unrest. After some pushing and shoving with police, the marchers rallied near the barricades, waving flags, singing and chanting.

Israeli police deployed in large numbers around the historic Old City, home to major religious sites for Jews, Christians and Muslims, out of concern that confrontations could further inflame an already tense situation during the Jewish holiday of Passover and the Muslim holy month of Ramadan.

Tensions have surged in recent weeks after a series of deadly attacks inside Israel, followed by military operations in the occupied West Bank. On Monday, Palestinian militants fired a rocket from the Gaza Strip into Israel for the first time in months, and Israel responded with airstrikes. That rocket was intercepted and there were no casualties from the exchange.

It came after repeated clashes between Israeli police and Palestinians at the Al-Aqsa mosque compound, known to Jews as the Temple Mount.