METULLA, Israel (AP) _ Israeli troops pulled out of their second-largest base in southern Lebanon overnight, quickening the pace of their withdrawal. Convoys of Israeli soldiers drove out of Lebanon at daybreak in tanks and jeeps Tuesday, honking horns, waving brigade banners and kissing the soil of their homeland.

The army described the predawn departure from the Bint Jbeil _ one of its Lebanon headquarters, in the western sector of Israel's rapidly emptying ``security zone'' _ as orderly. Some young soldiers called their mothers to let them know they were back in Israeli territory.

Lebanese guerrillas and their jubilant civilian sympathizers then swept into the town. Many of those in the crowd waved the flags of the main Shiite Muslim guerrilla groups Hezbollah and Amal and shouted pro-Hezbollah slogans.

Meanwhile, several busloads of Lebanese _ apparently troops of Israel's collapsing allied SLA militia and their families _ crossed over into Israel early Tuesday at the Rosh HaNikra border post.

Israel's security Cabinet, which met in late-night session, told Prime Minister Ehud Barak he had full authority to determine the pace of the pullout, but army radio cited high-ranking army officials as saying the withdrawal would be over within a few days.

The pullout initially was due to be completed by July 7.

As Israeli's troop withdrawal proceeded at full speed, tens of thousands of Israelis living near the border spent an uneasy night in bomb shelters, with the boom of artillery duels clearly audible just across the frontier.

The rapidly deteriorating situation in south Lebanon _ including concern that Israel's allied militia could be lurching toward collapse _ had brought calls from some to expedite Israel's troop pullout from the zone in south Lebanon where it has had a military presence for the past 22 years.

Haim Ramon, a Cabinet minister and confidant of Barak, said at the meeting that he hoped the pullout would be ``much earlier'' than the deadline Israel imposed on itself in July.

Ramon also told Israel's Channel 2 that once the troops are out of Lebanon, Israel will feel far less constrained in terms of reprisals if it is attacked.

``Up until now ... we could not react as we are capable of doing, using the full power of the (army),'' he said. ``The rules of the game are changing.''

Israel beefed up defenses on its northern border _ army tank transporters were seen Monday night on the road leading north _ and warned that attacks on either its troops or its northern communities would bring harsh reprisals, not limited to the battle zone in south Lebanon.

``If someone initiates attacks on Israeli soldiers, not to mention the settlements of the north, as we withdraw ... the response will be very painful,'' said Barak, speaking in the border town of Zarit. ``I don't recommend to anyone in the area to provoke a response from Israel.''

In Kiryat Shemona, the principal border town, loudspeakers blared orders to head into shelters after word came that two Lebanese civilians had been killed in the occupied zone.

In a crowded market, people grabbed their groceries and hurried off. Even youngsters like 12-year-old Efrat Ohana knew enough to take cover quickly.

``I was on the way home from school, and as my mother taught me, I ran with my bag to the shelter in the building and waited for my parents to come home from work,'' she said calmly.

Traffic heading south was heavy as some northerners opted to flee out of rocket range rather than spend a night in shelters.

Barak repeated Monday that Israel's troop pullout would be completed by its self-imposed deadline of July 7, but said the exact date will be decided ``according to ... Israel's considerations.''

One of those considerations is the state of Israel's allied militia, the South Lebanon Army, elements of which appear to be sliding into a state of chaos. Over the past few days, SLA militiamen have been abandoning outposts, deserting by the dozens and seeking shelter in Israel, apparently fearing for their lives.

With the pullback of the SLA, sympathizers of the Shiite Muslim Hezbollah guerrillas have in the past two days taken over a dozen villages, giving the guerrillas a foothold close by the Israeli border.

On Monday, five SLA men _ all senior officers, according to Israel radio _ crossed over into Israel near the communal farm of Milkhia to plead for asylum for themselves and dozens of relatives. Israel has promised to provide shelter to fleeing militiamen and their families.

SLA men remaining in Lebanon after the pullout face the threat of reprisals from Hezbollah, which led the fight to drive out Israel, and from the Lebanese government, which considers the SLA troops traitors and has sentenced some officers to death in absentia.

The Israeli daily Maariv, in Monday's editions, said senior Israeli military officers had ``great doubt'' as to whether the SLA could continue to function.

So rife was speculation about a speeded-up withdrawal timetable that the Defense Ministry issued a statement explicitly denying there was any order to pull out on June 1.

Worry is growing about SLA-abandoned weaponry falling into the hands of Hezbollah. On Monday, Israeli warplanes destroyed an SLA artillery battery in the central area of the occupied zone after it was abandoned by its crew, the army said.

Israeli officials said it had been known all along that a unilateral pullout from south Lebanon _ without any guarantees from Lebanon that it would prevent guerrilla attacks _ might not go smoothly.

Asked on Israel TV whether the situation had spun out of control, Israel's justice minister, Yossi Beilin, said: ``Anyone who spoke about withdrawal without an agreement understood it would be a withdrawal without rice being thrown at soldiers, and would not be simple.''