One of the worst mass casualty strikes on Israel in a year of war came not from dozens of Iranian ballistic missiles nor the repeated barrages of rocket fire launched by Hamas and Hezbollah. Instead, it was a single drone.

The unmanned aerial vehicle, laden with explosives, evaded Israel's multilayered air-defense system and slammed into a mess hall at a military training camp deep inside Israel, killing four soldiers and wounding dozens.

As the war between Israel and Lebanon's Hezbollah escalates, a United Nations peacekeeping force in Lebanon is increasingly in the crosshairs, with Israeli troops firing at the peacekeepers' headquarters and positions several times in the past week.

The peacekeepers belong to the 10,000-strong United Nations Interim Force in Lebanon, known as UNIFIL, who have been patrolling the border area between Lebanon and Israel for nearly 50 years.

Lebanese Christian Joseph Jarjour was hoping for a peaceful retirement at home in south Lebanon, but has instead found himself caught in the crossfire of the Israel-Hezbollah war.

"We're trapped," said the 68-year-old retired teacher in the southern village of Rmeish, around two kilometers (one mile) from the Israeli border.

Rescue workers searched through the rubble of a collapsed building in central Beirut on Friday morning, hours after two Israeli strikes hit the Lebanese capital, killing at least 22 people and wounding dozens.

The air raid was the deadliest attack on central Beirut in over a year of war, hitting two residential buildings in neighborhoods that have swelled with displaced people fleeing Israeli bombardment elsewhere in the country.

Israel’s ground invasion in Lebanon stretched into its second week, as Hezbollah fired hundreds of rockets deep into Israel — with no end in sight to the escalating conflict.

More than 1,400 people have been killed in Lebanon -- mostly in airstrikes -- and over a million displaced since the fighting intensified in mid-September. At least 15 Israeli soldiers and two civilians have been killed since the ground operation began, and more than 60,000 people have been displaced from towns along the border for more than a year.

Israel has promised to retaliate for Iran's massive missile attack last week. How it does so involves great risk, and could have major repercussions for the archenemies, the Middle East and the world.

Israel's options range from symbolic strikes on military targets to crippling attacks on Iran's vital oil industry or its secretive and heavily fortified nuclear program.

Sheikh Naim Qassem has been the acting head of Hezbollah since its longtime leader Sayyed Hassan Nasrallah was killed as part of an Israeli offensive that has taken out many of the group's senior officials.

Qassem made a defiant televised speech Tuesday, claiming that the group's military capabilities are intact and Israelis will only suffer further as fighting continues.

Israel's military struck outside the gates of a hospital in southern Lebanon without warning on Friday, killing seven paramedics and forcing the facility to close, the hospital director told The Associated Press a day after one of the most deadly attacks on health workers in the weeks since fighting escalated between Israel and Hezbollah.

The account of the Friday airstrikes that flung hospital doors off their hinges and shattered glass was the latest to detail attacks that Lebanon's health ministry says have killed dozens of health workers.

Israel launched a new air and ground offensive in northern Gaza Sunday, hours after pounding Beirut's southern suburbs in the heaviest bombardment since it stepped up its pursuit of Hezbollah last month.

The intensified campaign on two fronts, including an overnight strike on a Gaza mosque that killed 19, came as Israel remained on high alert ahead of memorial events to mark the surprise attack a year ago that triggered the ongoing war.

In just over a week, intensified Israeli strikes in Lebanon killed seven high-ranking commanders and officials from the powerful Hezbollah militant group, including the group's leader, Sayyed Hassan Nasrallah.

The move left Lebanon and much of the Mideast in shock as Israeli officials celebrated major military and intelligence breakthroughs.