The Israeli military and Hezbollah traded deadly attacks for a fifth straight day on Sunday, with the Lebanon-based militants striking Haifa and other towns deeper inside Israel.
World powers meeting in Russia Sunday appealed for an end to the violence, even as Israel warned of fierce retaliation for the Haifa attack, which killed eight Israelis.
Hours after the Haifa attack, Israeli airstrikes pounded the southern suburbs of Beirut on Sunday.
Twenty people were killed and 50 were wounded Sunday south of Beirut in an Israeli airstrike on the Lebanese port city of Tyre, according to Lebanese television.
Later Sunday, Hezbollah rockets hit three northern Israeli towns more than 40 kilometers (25 miles) south of the Lebanese border, the farthest south of any rocket attacks to date, the Israeli military said.
Minor injuries were reported when the missiles hit the towns of Nazareth, Afula and Givat E'la near Israel's border with the West Bank, Israeli officials said.
Those reports came shortly after the airport was struck in south Beirut, sending a fuel storage depot up in flames.
Hezbollah claimed responsibility for the attack on Haifa, saying it was responding to overnight Israeli airstrikes inside Lebanon.
One of the Hezbollah rockets hit a railway depot, killing at least eight and wounding 17 others -- six of them seriously -- Israeli medical services said.
The Israeli military said subsequent airstrikes hit buildings where Hezbollah members lived and worked.
The IDF said it targeted the villages of Tsur and Aitaron in south Lebanon. And in Beirut's southern suburbs, a building housing a Hezbollah radio station was leveled.
Israeli troops also used 155 mm howitzers to shell targets inside southern Lebanon that they said were used by Hezbollah to launch rockets.
Residents in southern Lebanon had been warned two to three hours in advance of the attacks, the IDF said.
Lebanese officials said Sunday that 104 people have been killed and 286 wounded in the fighting between Israel and Hezbollah militants that began Wednesday.
A total of 12 Israeli civilians and 12 Israeli military personnel have been killed since Wednesday. More than 100 others have been wounded.
Seven Canadians were killed and another three were wounded Sunday in southern Lebanon amid Israeli shelling and airstrikes, Canada's foreign ministry said.
Hezbollah: Just beginning
Hezbollah leader Hassan Nasrallah said Sunday that his fighters still have plenty of weapons and the will to keep fighting.
"Our fighters are ready," he said in a televised address in Arabic to the Lebanese people.
"As we surprised [Israel] in the sea, and as we surprised them in Haifa, we will surprise them with what's beyond Haifa," Nasrallah said.
He accused Israel of attacking civilian targets, while insisting that Hezbollah has aimed its rocket attacks only at the Israeli military.
"The enemy does not know our capabilities. ... We are still in the beginning," he said.
In Israel, Deputy Prime Minister Shimon Peres acknowledged that civilian casualties have occurred but said Israeli forces "are extremely careful" about distinguishing between Hezbollah and civilian targets.
"We are being attacked indiscriminately," he said.
Israeli Transportation Minister Shaul Mofaz said the missile contained Syrian ammunition.
"The Iranians supply Hezbollah with weapons and technology," said Mofaz, Israel's former defense minister. "Syria is taking part."
The weapon was a Katyusha rocket with a range of 35 to 40 kilometers (22-25 miles), IDF spokeswoman Miri Regev said. Haifa, Israel's third largest city, is about 35 kilometers south of the Lebanese border.
Iran rejected a similar Israeli assertion that it supplied Hezbollah the missile that struck an Israeli warship Friday, killing four Israeli sailors.
The Israeli military found the bodies of three of the sailors Sunday. The body of the fourth sailor had been found the day before.
Rockets also hit the northern towns of Akko and Nahariya on Sunday, and residents of northern Israel were told to take cover in bomb shelters.
Israel on alert as far south as Tel Aviv
The Israeli military warned residents as far south as Tel Aviv to raise their level of awareness, as the country is on alert against conventional weapons, according to the IDF.
The Israeli military said Hezbollah has fired more than 450 rockets into northern Israel since Wednesday.
Speaking before his weekly Cabinet meeting, Israeli Prime Minister Ehud Olmert said the attack "will have far-reaching implications" on Israel's relationship with its "northern neighbors."
A spokesman for the Italian government said Lebanon has been given a list of Israeli conditions for a cease-fire that includes the release of two Israeli soldiers captured by Hezbollah, the withdrawal of the group from south Lebanon and an end to rocket attacks on Israel.
The conditions were relayed to Lebanese Prime Minister Fouad Siniora in a phone call by Italian Prime Minister Romano Prodi, according to spokesman Silvio Sircana.
In Beirut's Parliament building, Siniora met during the afternoon with European Union Foreign Affairs and Security Chief Javier Solana.
"The gates of hell have been opened on Lebanon," Siniora told CNN. He called Israel's actions "disproportionate," and predicted they would encourage extremists.
In St. Petersburg, Russia, the Group of Eight countries issued a statement expressing "deepening concern" about the situation. But the G-8 countries are divided over who is to blame and how to move forward.