A previously unknown Islamist group took responsibility Thursday for the firing of two mortar shells at Mount Hermon a day earlier. It was the first time since the outbreak of the Syrian uprising that the area was targeted, and it led authorities to shut down the tourist area for several hours.

In a message posted online, the self-described Abdul Qader Husseini Battalions of the Free Palestine movement said it “attacked an observatory of the Zionist entity on the occupied Golan Heights with missiles on the anniversary of return, May 15, 2013, avenging the martyrs of return [who died] last year.”

The group was likely referring to clashes between Israeli troops and Palestinian refugees in Syria on Nakba Day in 2011 that left 13 dead after the border fence was breached.

Palestinians mark the Nakba, or catastrophe of the founding of Israel, every May 15.

“We do not celebrate, but rather avenge our martyrs as we tell the Zionist enemy that this is a battle of score settling,” the group wrote. “The operation included two missile barrages and was carried out at 5 a.m. Long live liberated Palestine.”

A video posted on Youtube on Wednesday purports to show the group firing the rockets.

There were no reported injuries or damage from the mortar fire. The area in the Hermon, the mountain range that straddles the Lebanese-Syrian border and the Golan Heights, was promptly closed to hikers for several hours on the Shavuot holiday.

Israel lodged a complaint over the attack with UNDOF, the United Nations Disengagement Observer Force, which oversees the buffer zone between Syria and Israel established by the Security Council in the wake of the 1973 Yom Kippur War.

On Wednesday, Israel Radio reported that Tehran had approached Damascus about letting Lebanese terror group Hezbollah open a new front against Israel from Syrian territory.

The Lebanese daily al-Akhbar suggested last week that Iran had “reached a final decision” to respond to reported Israeli airstrikes on a weapons transfer in Syria by “turning the Golan into a new Fatah-land. The front has become open to Syrians and Palestinians and anyone who wants to fight Israel.”

Mortar shells fired from within Syria have landed in the Golan Heights several times in previous months, and Israel has often returned fire.

Last Monday, two shells hit the Israeli Golan Heights near the town of Ramat Magshimim, but no injuries or damage were reported. The next day, another mortar hit the southern Golan Heights as a result of the spillover from fighting in Syria, again without casualties or harm caused during the incident.

Aaron Kalman contributed to this report.