The brief cross-border exchange was the first since Israel launched an offensive against the militant group Hamas on its southern border, in the Gaza Strip on Dec. 27.

It was unclear who had fired the rockets from Lebanon and whether it signaled the start of a wider conflict or was limited. But the exchange was certain to raise tensions between the militant group Hezbollah in southern Lebanon, which is a Hamas ally, and Israel. Hezbollah and Israel fought a brutal 34-day war in summer 2006.

No group immediately claimed responsibility for the rocket firing. The militant group Hezbollah had no immediate comment, and its TV station only carried the reports of the exchange without any commentary.

Radical Palestinian factions also have a presence in Lebanon. The Syrian-backed Popular Front for the Liberation of Palestine-General Command, for example, had warned it might open other fronts against Israel if the attacks on Gaza continued.

A Lebanese government official said the government was investigating the rocket firing and was in consultation with the U.N. peacekeeping force in southern Lebanon, which oversees a truce since the 2006 war, to determine who had fired the rockets into northern Israel.

“What happened today is a violation of Resolution 1701,” the Lebanese official said, referring to the U.N. resolution that ended the 2006 war. “The Lebanese government is still committed to this resolution and is against any violation,” said the official, speaking on condition of anonymity in line with government regulations.

Lebanese security officials, speaking on condition of anonymity in line with government regulations, said as many as three Katyusha rockets were fired into Israel from an area north of the Lebanese coastal village of Naqoura.

In Israel, police reported at least three rockets fell around the northern Israeli border town of Nahariya in the morning. Rescue services said at least one person was lightly wounded.

The Lebanese officials said Israelis fired back with about six artillery shells. TV stations said the shells crashed in a valley near a village about 3 kilometers (1.8 miles) north of the Israeli border.

There was no immediate report of casualties from the shells falling inside Lebanon.

Hezbollah is a strong ally of Hamas. But it had held its fire so far during the Israeli offensive in the Hamas-ruled Gaza Strip, which Israel has said is designed to stop Hamas from firing rockets into Israel.

Hezbollah has said it does not want to draw Lebanon into a war with Israel. But the group has said it’s ready to fight if attacked. -AP