Beirut, Lebanon ? Israel and Hezbollah fought bloody ground battles and exchanged fierce air and missile strikes Friday – including bombing raids that severed Lebanon’s last major supply link with Syria and the outside world, and the guerrillas’ deepest rocket attack inside Israel to date.

Loud explosions resounded early today in Beirut’s suburbs as Israeli warplanes renewed their onslaught, local media said. Israeli helicopters, meanwhile, attacked suspected Hezbollah positions in the southern city of Tyre, though Hezbollah’s TV station claimed that fighters repelled helicopter-borne troops who tried to land, killing one soldier. Israel declined to comment.

After days of desultory diplomacy, the U.S. said it was near agreement with France on a U.N. cease-fire resolution, possibly by early next week. But Israel and Hezbollah showed no signs of holding their fire.

Three Hezbollah rockets landed near Hadera, 50 miles south of the Israel-Lebanon border; 188 rockets rained on other towns, killing three Israeli Arabs.

Given the determination of both Hezbollah and Israel to look victorious when the conflict finally ends, the worst of the fighting still may lie ahead with the militant Shiite guerrilla fighters perhaps making good on their threat to rocket Tel Aviv and Israel launching an all-out ground offensive, pushing northward to the Litani River.

Israeli military officials said Friday they completed the first phase of the offensive, securing a four-mile buffer zone in south Lebanon, though pockets of Hezbollah resistance remained.

A large bomb creates a crater on the Maameltein bridge north of Beirut, Lebanon. Israel's pounding of Hezbollah positions across Lebanon expanded Friday with missiles targeting bridges in the Christian heartland north of Beirut for the first time. The Israeli attacks on the four bridges on the main north-south coastal highway linking Beirut to Syria severed the only remaining major road link.

Defense Minister Amir Peretz told top army officers to begin preparing for a push to the Litani, about 20 miles north of the border – a move that would require Cabinet approval. Peretz vowed his forces would complete “the whole mission” of driving guerrilla fighters out of missile range, a defiant response to the Hezbollah leader’s threat to launch missiles into Israel’s largest city.

Warning of the potential for a larger war, U.N. Secretary-General Kofi Annan called for an immediate end to hostilities and said peacekeepers should be sent to southern Lebanon. He also called for the disarmament of Hezbollah and a redrawing of Lebanon’s borders with Israel and Syria.

“Otherwise, we may see explosions elsewhere,” Annan said.

Israeli airstrikes destroyed four key bridges after dawn Friday, severing Beirut’s final major connection to Syria and raising the threat of severe shortages of food, gasoline and medicines within days. The attack in the Christian heartland just north of Beirut killed four civilians and a Lebanese soldier.

Israel said it targeted the bridges to stop the flow of weapons to Hezbollah from Iran through Syria. Those weapons include missiles and sophisticated anti-tank missiles said to be responsible for most of the 44 Israeli soldiers killed in more than three weeks of fighting.

However, aid workers said the destroyed highway was a vital conduit for much-needed food and supplies, with Christiane Berthiaume of the World Food Program calling it Lebanon’s “umbilical cord.”

“This (road) has been the only way for us to bring in aid. We really need to find other ways to bring relief in,” she said in Geneva.

Hospitals were in danger of closing soon because medicines, hospital supplies and fuel for generators was fast running out. Staples like milk, rice and sugar were growing short across the country. Lines at Beirut filling stations stretch longer by the day.

Dr. George Tomey, acting president of the American University of Beirut, said its Medical Center, one of the prime and best known medical facilities in the Middle East, would stop receiving new patients as of Monday, except for emergency cases.

Dr. Ghassan Hammoud, who runs a 320-bed hospital packed with war wounded in the southern port city of Sidon, said he might have to shut down within 10 days.