Israel and Hezbollah traded strikes again Tuesday as the death toll from a massive Israeli bombardment climbed to nearly 560 people and thousands fled from southern Lebanon with the two sides on the brink of all-out war.

Displaced families slept in shelters hastily set up in schools in Beirut and the coastal city of Sidon. With hotels quickly booked to capacity or rooms priced beyond the means of many families, those who did not find shelter slept in their cars, in parks or along the seaside.

Issa Baydoun fled the village of Shihine in southern Lebanon when it came under bombing and came to Beirut in a convoy of cars with his extended family. They slept in the vehicles on the side of the road after discovering that the shelters were full.

"We struggled a lot on the road just to get here," he said.

Baydoun rejected Israel's contention that it hit only military targets.

"We evacuated our homes because Israel is targeting civilians and attacking them," he said. "That's why we left our homes, to protect our children."

Well-wishers offered up empty apartments or rooms in their houses in social media posts, while volunteers set up a kitchen at an empty gas station in Beirut to cook meals for the displaced.

In the eastern city of Baalbek, the state-run National News Agency reported that lines formed at bakeries and gas stations as residents rushed to stock up on essential supplies in anticipation of another round of strikes on Tuesday.

Meanwhile, the border crossing with Syria saw massive traffic jams as a result of people escaping from Lebanon to the neighboring country.

The Lebanese militant group Hezbollah said it launched missiles overnight at eight sites in Israel, including an explosives factory in Zichron, 37 miles from the border.

The Israeli military said Tuesday morning that 55 rockets were fired from Lebanon into northern Israel, setting fires and damaging buildings. Military officials said they carried out dozens of airstrikes on Hezbollah targets, including on a cell that fired rockets overnight, and that tanks and artillery struck targets near the border.

Galilee Medical Center, a northern Israel hospital, said that two patients arrived with minor head injuries from a rocket falling near their car. Several others were being treated for light wounds from running to shelters and traffic accidents when alarms sounded.

The renewed exchange came after Monday's barrages racked up the highest death toll in any single day in Lebanon since Israel and Hezbollah fought a bruising monthlong war in 2006.

Israel said it targeted sites where Hezbollah had stored weapons. Data from American fire-tracking satellites analyzed Tuesday by The Associated Press showed the wide range of Israeli airstrikes aimed at southern Lebanon, covering an area of over 650 square miles.

NASA's Fire Information for Resource Management System typically is used to track wildfires across rural areas of the U.S. However, it can also be used to track the flashes and burning that follow airstrikes. That's particularly true when an airstrike ignites flammable material on the ground, such as munitions or fuel.

Data from Monday showed significant fires breaking out across southern Lebanon and in the Bekaa Valley. Several areas showed intense, multiple fires, including near the southern coastal town of Naqoura, which hosts a base for the U.N. peacekeeping mission in southern Lebanon known as UNIFIL. Others were in mountainous rural areas or villages.

The sides appear on the verge of war again after tensions have steadily escalated over the last 11 months. Hezbollah has been firing rockets, missiles and drones into northern Israel in solidarity with the Palestinians and its ally Hamas, a fellow Iran-backed militant group, in Gaza.

Israel has responded with increasingly heavy airstrikes and the targeted killing of Hezbollah commanders while threatening a wider operation.

Thousands of Lebanese fled the southern part of the country on Monday after the Israeli military ordered people to evacuate areas where it accuses Hezbollah of positioning rocket launchers and other weapons, in the biggest exodus since the monthlong war waged 18 years ago.

The Lebanese Health Ministry said the strikes since Monday killed at least 558 people, including 50 children and 94 women, and wounded more than 1,800 people — a staggering one-day toll for a country still reeling from a deadly attack on communication devices last week.

Nearly a year of cross-border fire had already emptied out communities near the border, displacing tens of thousands of people on both sides. Israel has vowed to do whatever it takes to ensure its citizens can return to their homes in the north, while Hezbollah has said it will keep up its rocket attacks until there is a cease-fire in Gaza, which appears increasingly remote.

The Israeli military says it has no immediate plans for a ground invasion but is prepared for one, after moving thousands of troops who had been serving in Gaza to the northern border. It says Hezbollah has launched some 9,000 rockets and drones into Israel since last October, including 250 on Monday alone.

The military said Israeli warplanes struck 1,600 Hezbollah targets Monday, destroying cruise missiles, long- and short-range rockets and attack drones, including weapons concealed in private homes. Lebanese officials have said many of the victims were civilians, including more than 90 women and children killed.

Israel estimates Hezbollah has some 150,000 rockets and missiles, including guided missiles and long-range projectiles capable of striking anywhere in Israel.

Monday's escalation came after a particularly heavy exchange of fire Sunday. Hezbollah launched around 150 rockets, missiles and drones into northern Israel in retaliation for strikes that killed a top commander and dozens of fighters.

Last week, thousands of communications devices, used mainly by Hezbollah members, exploded in different parts of Lebanon, killing 39 people and wounding nearly 3,000, many of them civilians. Lebanon blamed Israel, but Israel did not confirm or deny responsibility.