The Israeli military says its warplanes are hitting Hezbollah targets in Lebanon after detecting moves to fire missiles and rockets into Israel.
“In a self-defence act to remove these threats, the IDF (Israel Defense Forces) is striking terror targets,” IDF spokesman Daniel Hagari said.
Israel said Lebanese civilians had been warned to immediately leave areas where Hezbollah, an Iran-backed Shia Muslim group, was operating.
Shortly afterwards, Hezbollah said it had launched a large-scale drone attack on Israel in response to last month’s killing of the group’s senior military commander.
Across northern Israel sirens warning of incoming rockets were heard sounding early on Sunday.
There were no immediate reports of any injuries.
Israeli Prime Minister Benjamin Netanyahu said he was convening an urgent meeting of his security cabinet.
Israel has been exchanging fire with the Lebanon-based militant group since the start of the war last October with Hamas in the Gaza Strip.