Saudi forces have ended their offensive on assailants as most of the 50 European, American and Arab hostages have been released. A Saudi security official said an attacker believed to be the leader in the hostage crisis in the eastern oil city of Khubar was also arrested on Sunday. Another two hostage takers were "in the process of being arrested," he said. However, security officials would not comment on the whereabouts or conditions of the hostages, saying only that the compound was surrounded. The crisis ended about 25 hours after it began on Saturday with attackers opening fire and engaging in shootouts with Saudi security forces at the Oasis compound and two oil-related facilities. The assailants had taken more than 50 foreign hostages. A security guard said on Sunday that some of the hostages had been killed. Earlier reports said 10 people had died. A police official at the scene on Sunday said most of the hostages had been released and evacuated to hotels or remain with security officials. Earlier, Saudi commandos raided the compound. Witnesses saw three twin-bladed military helicopters dropping special forces on to the roof of a building in the compound amid gunfire. An explosion was heard as the attackers, armed with grenades and machineguns, exchanged gunfire with the security forces, who included special forces units. Prior to the storming, security forces had sealed off roads leading to the site and driven journalists away from the scene of the hostage drama. **Booby traps*** An earlier attempt to storm the building was aborted when Saudi forces discovered it was booby-trapped with explosives. Ambulances were seen racing to the apartment building where at least four hostage takers were holed up with their hostages in the Oasis compound -a village-like facility dotted with villas and restaurants- and populated by Arab and western expatriates. Security forces used floodlights after they cut power supplies to the building where the attackers were barricaded. About 200 members of the special forces attached to the Saudi navy were deployed at the site to join other units from the army and special security forces. Security sources said the building where the hostages were being held had been booby-trapped. **Laying siege*** Security forces had been encircling the armed men for several hours after the suspected al-Qaida fighters went on a shooting spree earlier on Saturday, attacking the compound and two oil-related facilities. Sixty residents were evacuated from the compound in armoured vehicles and ambulances. The Swedish foreign ministry, meanwhile, said a Swede might have been among those killed in Saturday's attacks. "Our embassy has been informed by Saudi authorities that one of the people killed may have been of Swedish origin," Foreign Ministry spokesman Tobias Nilsson said. "The ambassador will travel to Khubar tomorrow morning to investigate the information," Nilsson said. **ABB clarification*** Swiss-Swedish engineering group ABB, which lost five foreign and two local employees to gun attacks in Saudi Arabia earlier this month, said none of its staff had been injured or killed in the latest attacks. "None of our people were hurt," company spokesman Per-Lennart Berg said. Swedish ambassador to Saudi Arabia, Aake Karlsson said between 700 and 800 Swedes live in the country, mainly around Riyadh and near Jeddah. Very few live in the Khubar area, he said. **PHOTO CAPTION*** Saudi police and security stand near the three covered dead bodies of victims at the Corniche Road in front of Al-Khubar Petroleum Center in Khubar in Saudi Arabia, Saturday May 29, 2004. (AP)