Dozens of people have been killed by Israeli strikes in Lebanon, including 20 who died after a strike flattened a multi-story residential building in central Beirut overnight, according to Lebanese officials.

The Israel Defense Forces continued its intense airstrike and ground campaigns in Gaza -- particularly in the north of the strip -- and in Lebanon, with Israeli attacks on targets nationwide including in the capital Beirut.

Red Alert sirens were activated in central Israel by a barrage of six rockets fired from Lebanon Sunday morning. The barrage also set off alarms in areas of northern Israel. No casualties have been reported so far.