AL-KHOBAR (Saudi Arabia), May 29: Eighteen people, including seven foreigners, were killed when militants launched a series of attacks in this coastal city on Saturday.

The militants were holding an unspecified number of hostages in the prestigious Oasis complex till late in the night, sources said.

Security forces had stormed the villas and residents were evacuated, yet some people were still in the captivity of attackers.

Commandos were airlifted into the city from Riyadh to handle the situation obtaining after the attacks, the responsibility for which was purportedly claimed Al Qaeda.

Some other sources said all the women and children hostages were released earlier by the captors, including five Lebanese. They were set free after the Lebanese ambassador to the kingdom went into the compound and negotiated their release.

Sources said the militants made their way into their targets in the morning. They attacked offices and the residential area of the Arab Petroleum Investment Corporation (Apicorp) on the old Dammam-Khobar coastal road.

According to a Pakistani resident of the compound, a British employee of Apicorp, a 10-year-old Egyptian boy and two security guards were killed.

In a similar raid on the Petroleum Centre, a few kilometres from Apicorp, many people were killed. The exact number of those killed there is unknown. However, according to some journalists, at least four people, including a Pakistani and a US citizen, died when the attackers opened fire on the third floor of the building. It houses the offices of the oil concern Schlumberger and a company, Resource Saudi Arabia Ltd.

The third incident took place in the Oasis residential compound which also houses a hotel. The attackers knocked at some of the doors in the block and asked for the nationality of the residents. Westerners, particularly the Americans and the British, were reported to be the targets.

Sources said the manager of the hotel's restaurant, a Western national, was killed. The local King Faisal mortuary received 18 bodies, medical sources said.

Saudi authorities did not give much detail about the gory incidents till late night.

An interior ministry source had earlier told the press that "security forces are dealing with them (the attackers) according to the situation".

The ministry's statement confirmed death of and injuries to a number of Saudi citizens and expatriates but refrained from giving any specific number.

The attacks on the petroleum centre and the Apicorp centre are being seen as an attempt to damage the oil and energy infrastructure of the kingdom as almost 90 per cent of the Saudi oil is found in this eastern province.

The attacks came two days after a message from Abdul Aziz al-Muqren, who claims to be the leader of Al Qaeda in the kingdom, warned of more attacks in the kingdom. A statement from Al Qaeda posted on a website purportedly claimed responsibility for the raids, saying its Jerusalem Squad had carried out the attacks. However, authenticity of the claim could not be independently verified.

The owner of the Saad group, which also owns the Oasis compound, where reportedly seven gunmen have taken about 45-50 people hostage, told a local TV channel that the situation inside the compound "is beyond imagination." He did not elaborate.

AFP adds: Three Western nationals escaped from the Oasis residential compound and said they had seen the body of a woman drenched in blood.

The US embassy in Riyadh confirmed one American was among the dead.

An Egyptian diplomatic source named the 10-year-old as Rami Samir al-Ghunaimi.

GUNFIRE & BLAST: Gunfire and a blast were heard at the Oasis complex as Saudi security forces prepared to storm a building where gunmen were holding captives of various nationalities, an AFP correspondent at the scene said.

The thud of an explosion was heard and gunfire crackled hours after gunmen had holed up in the six-storey building.

The US embassy in Riyadh reiterated its call on US citizens to leave Saudi Arabia following the attacks.

"In light of the attack in Yanbu on May 1 and this latest attack in Al-Khobar, the embassy reiterates its previous warning strongly urging American citizens to depart the country," said a message read to AFP by an embassy spokesperson.