By RAVI NESSMAN, Associated Press Writer Ravi Nessman, Associated Press Writer – 11 mins ago

COLOMBO, Sri Lanka – The United Nations called the killing of hundreds of ethnic Tamil civilians in a weekend artillery attack in northern Sri Lanka a "bloodbath" amid reports Monday that the war zone was heavily shelled for a second straight night.The initial artillery attack — which lasted from Saturday evening into Sunday morning — killed at least 378 civilians and wounded more than a thousand more, according to a health official inside rebel-controlled territory.A rebel-linked Web site blamed the attack on the government, while the military accused the beleaguered Tamil Tigers of briefly shelling their own territory to gain international sympathy and force a cease-fire.About 6 p.m. Sunday, a new round of shelling pounded the area, according to a government health official, who spoke on condition of anonymity because he was not authorized to speak to the media.The TamilNet Web site said many more civilians were killed in the second attack and that the death toll from the two days of violence was likely in the thousands.Reports of the fighting are difficult to verify because the government bars journalists and aid workers from the war zone, but the U.N. confirmed a heavy toll from the first attack over the weekend.That attack marked the bloodiest assault on ethnic Tamil civilians since the civil war flared again more than three years ago. Health officials said a hospital in the war zone was overwhelmed by casualties, and the death toll was expected to sharply rise."The U.N. has consistently warned against the bloodbath scenario as we've watched the steady increase in civilian deaths over the last few months," U.N. spokesman Gordon Weiss said Monday. "The large-scale killing of civilians over the weekend, including the deaths of more than 100 children, shows that that bloodbath has become a reality."U.N. figures compiled last month showed that nearly 6,500 civilians had been killed in three months of fighting this year as the government drove the rebels out of their strongholds in the north and vowed to end the war.About 50,000 civilians are crowded into the 2.4 mile- (4 kilometer) long strip of coast along with the separatists, who have been fighting for 25 years for a homeland for minority Tamils.The government has brushed off international calls for a humanitarian truce, saying any pause in the fighting would give the rebels time to regroup.The initial attack began Saturday evening soon after a Red Cross ship that had been evacuating wounded civilians left the war zone, health officials said.Artillery pounded the area throughout the night, forcing thousands to huddle in makeshift bunkers, said Dr. V. Shanmugarajah, a health official in the region.Hours after the attack, the dead and wounded continued to pour into the hospital, he said. As of Sunday afternoon, the bodies of 378 civilians had been brought in and were being buried by volunteers, but the death toll was likely far higher since many families buried their dead where they fell, he said.TamilNet said rescue workers had counted 1,200 civilians killed in the attack. The Web site initially reported that the rebels' military spokesman, Rasiah Ilanthirayan, was among the dead, but later said only that he was seriously wounded.Bodies were laid out in rows on the mud outside the hospital, some of their faces covered with mats and sheets, according to photos from the area. One small boy was stripped to the waist, his head covered in a bloody bandage and his mouth agape.The hospital was struggling to cope with the 1,122 wounded civilians amid a shortage of physicians, nurses and aides made treatment difficult, Shanmugarajah said."We are doing the first aid and some surgeries as quickly as we can. We are doing what is possible. The situation is overwhelming; nothing is within our control," he said. More than half the hospital staff did not turn up for work because their homes were attacked and many of the wounded went untreated for more than 24 hours, said the other health official, who declined to be named. Suresh Premachandran, an ethnic Tamil lawmaker, said the assault was the deadliest attack on civilians since the 1983 anti-Tamil riots that killed as many as 2,000 people and helped trigger the civil war. "In the name of eliminating terrorism, the Sri Lankan government massacres its own citizens. It is absolutely unacceptable," he said, calling for the international community to intervene. TamilNet also blamed the attack on the Sri Lankan forces, which rights groups have accused of bombing and shelling the war zone despite its pledge to stop using heavy weapons. The Sri Lankan military denied firing the artillery and said they witnessed the rebels firing mortar shells from one corner of the coastal strip into another section heavily populated with civilians for one hour Sunday morning. "I think the LTTE (Liberation Tigers of Tamil Eelam) is now trying to use these people as their last weapon to show the world that the army is firing indiscriminately and stop this offensive," military spokesman Brig. Udaya Nanayakkara said. Human rights groups have accused the rebels of holding the civilians as human shields and shooting some who tried to flee. Human Rights Watch on Saturday accused the military of repeatedly shelling and bombing hospitals in the war zone.