Hundreds of Beirut residents fled their homes late on Sunday after Israel said it was preparing attacks on sites linked to the financial operations of the Hezbollah militant group and told people to leave those areas of Lebanon's capital immediately.

Soon after the Israeli warning, several blasts were heard and a large fire was seen in Beirut's southern suburbs. There was no immediate information on what caused the explosions, or details of if there were any casualties.

Panicked crowds clogged the streets and caused traffic jams in some parts of Beirut as they tried to get to neighbourhoods thought to be safer, witnesses said.

"Residents of Lebanon, the IDF [Israel Defence Forces] will begin attacking infrastructure belonging to the Hezbollah Al-Qard Al-Hassan Association — get away from it immediately," the Israeli military's spokesperson said in a statement on X, formerly Twitter.

Al-Qard Al-Hassan — which the U.S. has said is used by Iran-backed Hezbollah to manage its finances — has more than 30 branches across Lebanon, including 15 in densely populated parts of central Beirut and its suburbs.

There was no immediate statement from the organization, Hezbollah or the Lebanese government.

Asked by journalists whether the branches could be considered military targets, a senior Israeli intelligence official said: "The purpose of this strike is to target the ability of Hezbollah economic function both during the war but also afterwards to rebuild and to rearm ... on the day after."

Cross-border fighting between Israel and Hezbollah erupted a year ago when the group began launching rockets in support of Hamas after the Palestinian militant group led attacks on Israel on Oct. 7, 2023.

During those attacks, Hamas-led militants killed 1,200 people and took 250 hostages, according to Israeli tallies. Israel's military response in Gaza has killed more than 42,500 people and made most of Gaza's 2.3 million people homeless, Palestinian officials say.

At the start of October, Israel launched a ground assault inside Lebanon in an attempt to stabilize the border region for its citizens who had fled rocket attacks in northern Israel.

Escalating attacks in Lebanon and Gaza

Israel has intensified its military campaigns both in Gaza and Lebanon, days after the killing of Hamas leader Yahya Sinwar raised hopes of an opening for ceasefire negotiations to end more than a year of conflict.

With U.S. elections approaching, officials, diplomats and other sources in the region say Israel is seeking through military operations to try to shield its borders and ensure its enemies cannot regroup.

Israel is also preparing to retaliate for an Iranian missile barrage earlier this month, though Washington has pressed it not to strike Iranian energy facilities or nuclear sites.

WATCH | No one wins' in wider Middle East war, Pentagon warns:

'No one wins' in wider Middle East war, Pentagon press secretary warns

CBC chief political correspondent Rosemary Barton speaks with the Pentagon's press secretary, Maj.-Gen. Patrick Ryder, about Israel’s potential responses to Iran’s ballistic missile attack and the threats of a wider regional war.

Earlier on Sunday, Israel said it hit Hezbollah's intelligence headquarters and an underground weapons workshop in Beirut. Fighter jets killed three Hezbollah commanders, the Israeli military said.

Hezbollah made no immediate comment on those strikes but said it had fired missiles at Israeli forces in Lebanon and at a base in northern Israel.

A 41-year-old Israeli colonel was killed, and another officer was wounded in combat in northern Gaza on Sunday, the Israeli military said. Israel's Channel 12 and public broadcaster Kan reported an explosive device had gone off under a tank.

In Gaza, Palestinian officials said rescuers were still recovering people from the rubble after an Israeli attack on the northern city of Beit Lahiya that left 87 people dead or missing on Saturday, according to the Health Ministry — one of the highest death tolls in months from a single attack.

The strike came two weeks into a major assault around Jabalia, just south of Beit Lahiya, where Israel says its troops have been trying to root out remaining Hamas fighters.

Israel said the strike hit a Hamas target, questioning an earlier death toll of 73 released by the Hamas media office.

Hamas-led militants killed 1,200 people and took 250 hostages in the attack on Israel on Oct. 7 last year that sparked the war in Gaza, according to Israeli tallies.

Israel's military response in Gaza has left more than 42,500 people dead and has made most of Gaza's 2.3 million people homeless, Palestinian officials say.

Over the last year, Lebanese officials estimate that more than 2,400 people have been killed and more than 1.2 million people displaced in Lebanon. Fifty-nine people have been killed in northern Israel and the occupied Golan Heights over the same period, say Israeli authorities.