Saudi security forces say at least 16 people have been killed in attacks by militants on foreigners in eastern Saudi Arabia.
Officials say a 10-year-old Egyptian boy and an American are among those confirmed dead.
Saudi security forces stormed a foreigners' compound in Khobar, after the militants who carried out the attacks holed up there with an unknown number of hostages.
There are no immediate details about the outcome of the operation. Police have surrounded the Oasis compound and ambulances are standing by.
Earlier, the attackers released five Lebanese who were among the hostages seized at the facility, which houses oil company offices.
A group calling itself "al-Qaida in the Arabian Peninsula" has claimed responsibility for the attacks, saying it is fighting U.S. companies that are stealing Muslim oil wealth.
Earlier this month, militants killed at least five Westerners at an energy complex in the Red Sea city of Yanbu.
Saudi Arabia launched a high-profile crackdown on terrorists following last year's attacks on housing compounds in the capital, Riyadh. A string of suicide bombings last year killed 50 people, including nine Americans. Those attacks also were blamed on al-Qaida.
Information for this report is provided by AFP and Reuters.