Israel-Gaza-Lebanon updates: IDF orders evacuations in Beirut as huge blast hits city

The British government announced Monday that it chartered a commercial flight out of Lebanon for citizens wishing to leave the country.

British nationals, their spouse or partner and children under the age of 18 are eligible, a Foreign Office press release said. "Vulnerable" citizens will be prioritized, it added.

The flight is scheduled to depart Beirut-Rafic Hariri International Airport on Wednesday.

Foreign Secretary David Lammy said the situation in the country "is volatile and has potential to deteriorate quickly."

"The safety of British nationals in Lebanon continues to be our utmost priority," he added.

"That's why the U.K. government is chartering a flight to help those wanting to leave. It is vital that you leave now as further evacuation may not be guaranteed."

-ABC News' David Brennan

Lt. Col. Avichay Adraee -- the Israel Defense Forces' spokesperson for Arab media -- warned residents of southern Lebanon on Tuesday morning that "heavy fighting" is now underway in the region.

"Hezbollah elements," he said, are "using the civilian environment and the population as human shields to launch attacks."

Adraee told residents not to move vehicles from the north to the south of the Litani River, which is around 18 miles north of the Israeli border. Israel previously demanded that all Hezbollah forces withdraw north of the waterway in accordance with the United Nations Security Council resolution that sought to end the 2006 border war.

"This warning is in effect until further notice," Adraee said.

The IDF said Monday that its ground offensive into Lebanon was underway, following a week of punishing airstrikes and targeted killings across the country.

The IDF described the operations as "limited, localized, and targeted ground raids based on precise intelligence against Hezbollah terrorist targets and infrastructure in southern Lebanon."

A senior U.S. official told ABC News that the incursion is expected to be significant but not "major." Lebanese leaders, meanwhile, are calling for an immediate ceasefire and the implementation of the 2006 U.N. resolution that would see Hezbollah forces leave southern Lebanon.

-ABC News' Jordana Miller and Ghazi Balkiz

After Israeli forces began the ground incursion into southern Lebanon, at least 10 projectiles crossed over into northern Israel, according to the IDF.

"Following the sirens that sounded in the area of Meron in northern Israel, approximately 10 projectiles were identified crossing from Lebanon," the IDF said in a statement Monday.

"Some of the projectiles were intercepted and a number of projectiles fell in open areas," the IDF said.

Israeli forces have begun a ground incursion into southern Lebanon, a spokesperson for the IDF said in a statement.

The IDF described the operations as "limited, localized, and targeted ground raids based on precise intelligence against Hezbollah terrorist targets and infrastructure in southern Lebanon."

"The IDF is continuing to operate to achieve the goals of the war and is doing everything necessary to defend the citizens of Israel and return the citizens of northern Israel to their homes," the statement said.