Four rockets were fired from southern Lebanon into the Western Galilee region in Israel on Thursday afternoon. There were no immediate reports of casualties or damage.
One of the rockets fell on the outskirts of a small town near Nahariya where several residents were treated for shock.
The Iron Dome defense system reportedly intercepted at least one rocket.
The red alert siren sounded in the cities of Nahariya, Acre, and Kiryat Shmona, and residents reported hearing explosions.
Lebanese media outlets reported that two rockets, identified as Katyushas, were launched at Israel from the Al Kalila region in the Tyre district.
Israel Defense Forces (IDF) sources denied Lebanese media reports that any retaliation across the border had taken place. IDF Spokesman Brigadier General Yoav (Poly) Mordechai said that according to IDF estimates, international jihadists are responsible for the rocket fire at Israel.
"The first identification (of the rockets) was a launch from the village of Kalila south of Tyre, we assume representatives of the international Jihad movement," he said in a statement.
The army said it was looking into the incident and called on northern residents to remain close to bomb shelters, though they could go back to their normal routines.
A resident of Kibbutz Evron, near Nahariya, told the Ynet news site that the alarm sounded after “two booms” were heard, and that the residents quickly moved into bomb shelters.
“I heard booms,” a resident of Nahariya told Channel 2. “Everyone is in the bomb shelters.”
He said that residents hadn’t heard alarms for seven years — since the 2006 Second Lebanon War.