BEIRUT — A blast injured several United Nations technical observers outside a southern Lebanese border town on Saturday, the U.N. peacekeeping mission in the area said — an incident two security sources told Reuters was the result of an Israeli strike.

The Israeli military’s spokesman, Avichay Adraee, denied that Israeli forces hit a vehicle belonging to the U.N. peacekeeping mission in southern Lebanon, UNIFIL, near the town of Rmeish.

When asked to clarify whether its forces had hit any non-U.N. vehicles, the IDF told NBC News, “We did not strike in the area.”

In a statement, UNIFIL said that three military observers from the U.N. technical observer mission, UNTSO, and one Lebanese language assistant on a foot patrol along the Blue Line were injured “when an explosion occurred near their location.”

“They have now been evacuated for medical treatment,” the statement added. UNIFIL said it was now investigating the origin of the explosion, and has so far not attributed the strike to Israel.  

UNTSO, which monitors the demarcation line between Lebanon and Israel is unarmed. UNIFIL is an armed peacekeeping mission.

“All actors have a responsibility under international humanitarian law to ensure protection to non-combatants, including peacekeepers, journalists, medical personnel, and civilians,” UNIFIL said. “We repeat our call for all actors to cease the current heavy exchanges of fire before more people are unnecessarily hurt.”

Israel has been trading fire with the Lebanese armed group Hezbollah in southern Lebanon for nearly six months, in parallel with its war with Hamas in Gaza.

Hostilities between Israel and Lebanon have been escalating in recent days. Wednesday became the deadliest day in more than five months of fighting along the border, after a series of Israeli airstrikes killed 16 people in Lebanon, and a barrage of Hezbollah rockets killed one Israeli man.

Israel’s shelling of Lebanon has killed nearly 270 Hezbollah fighters, but has also killed around 50 civilians — including children, medics and journalists — and hit both UNIFIL and the Lebanese army.

In November, UNIFIL said one of its patrols was hit by Israeli gunfire in southern Lebanon, without leaving casualties.

UNIFIL last month said that the Israeli military violated international law by firing on a group of clearly identifiable journalists, killing a Reuters journalist. Israel denies targeting the reporters.