BEIRUT, Lebanon, Friday, July 14 — Israel imposed a full naval blockade on Lebanon on Thursday and put Beirut’s international airport out of commission, and the militant group Hezbollah loosed a hail of rockets and mortar shells that killed two Israelis and sent thousands into bomb shelters. A day after cross-border raids by Hezbollah fighters brought Israeli troops into Lebanon in force for the first time in six years, Israel sent punishing airstrikes deeper into the country, hitting all three runways at Rafik Hariri International Airport, two Lebanese Army bases. Early on Friday, it struck Hezbollah offices in south Beirut and the main highway between the capital and Damascus, Syria, and later, Reuters reported, a base for pro-Syrian Palestinian guerrillas a few miles from the Syrian border. The Lebanese government said 53 Lebanese civilians had died since Wednesday, including one family of 10 and another of 7 in the southern village of Dweir. More than 103 have been wounded, the Lebanese said. Lebanese residents hoarded canned goods and batteries as lines at gas stations stretched for blocks. Supermarkets and bakeries were flooded. It felt, many said, as if the civil war that ended 15 years ago was back. Israel said that the Lebanese government was responsible for the actions of Hezbollah, which is a member of the governing coalition, and that the cross-border raid that captured two Israeli soldiers on Wednesday was an unprovoked act of war by a neighboring state. Senior Israeli officials said that the military had been unleashed to cut off Lebanon, permanently drive Hezbollah forces back from the border and punish the government for not upholding a United Nations directive to disarm and control the group. Israel’s military chief of staff, Lt. Gen. Dan Halutz, warned that “nothing is safe” in Lebanon and that Beirut itself, especially Hezbollah offices and strongholds in southern Beirut, would be a target. Hezbollah fired more than 120 Katyusha rockets and mortar shells into Israel on Thursday, Israeli officials said. The barrage killed a woman on her balcony in Nahariya and a man in Safed, and wounded more than 100 other Israelis in some 20 towns and villages, including Haifa, Safed and Carmiel. Israeli officials said it was the first time Haifa had been hit by rocket fire from Lebanon. Hezbollah said it was using a new rocket, called Thunder 1, that is more advanced than the standard Katyusha, which does not have enough range to reach the 18 miles between the border and Haifa. Thousands of Israelis in the north spent the night in bomb shelters as Hezbollah warned that Israeli attacks on southern Beirut would be met by rocket attacks on Haifa, a port city of 250,000 people. Thursday evening, two rockets landed near the city’s Stella Maris Church. The rapid surge in fighting on a second front, two weeks after Israel entered Gaza to try to secure the release of another captured soldier, alarmed Arab and Western governments and drove up the price of oil. The European Union on Thursday criticized Israel for “the disproportionate use of force” in Lebanon “in response to attacks by Hezbollah on Israel,” according to a statement issued by the union’s current Finnish presidency. It said that “the imposition of an air and sea blockade on Lebanon cannot be justified.” The Israeli military said it struck the airport because it is “a central hub for the transfer of weapons and supplies to the Hezbollah terrorist organization.” President Bush, in remarks in Germany, said that “Israel has the right to defend herself,” but he also called for care, warning Israel not to weaken the government in Lebanon. “There are a group of terrorists who want to stop the advance of peace,” Mr. Bush said. “The soldiers need to be returned.” The Palestinian president, Mahmoud Abbas, warned that Israel’s Lebanon offensive “is raising our fears of a new regional war” and urged world powers to intervene. The Lebanese government, which has said that it had nothing to do with the raid by Hezbollah, called for a cease-fire, saying that all means should be used to end “open aggression” against the country. But Israeli officials said there would be a long campaign to restore the country’s security, both along its southern border with Gaza and its northern one with Lebanon. The Israelis want to restore their military credibility with the Palestinian militants and the Hamas government in Gaza and with Hezbollah, and say they intend to make the current campaign painful for both sets of antagonists. Neither Israel’s prime minister, Ehud Olmert, nor its defense minister, Amir Peretz, has the kind of long military experience previous holders of their positions have had, and the two have been in power for only several months. Some Israeli commentators argued that this made it all the more necessary for an unambiguous military response. The Israelis say they want the message to get across to Syria and Iran, the countries widely considered to be the main sponsors of Hezbollah and Palestinian militancy.