A nationwide manhunt is under way in Saudi Arabia for at least three Islamic militants who evaded capture after a bloody 25-hour hostage siege in Khobar.
Police have been checking cars throughout the city
Police have set up checkpoints to catch the gunmen who killed 22 people and took about 50 foreigners hostage.
Officials say the group's leader was wounded and captured, but that the others escaped using hostages as human shields and then hijacking a car.
But one hostage has claimed security forces allowed the gunman to escape.
The Interior Ministry said 41 hostages were freed on Sunday morning when Saudi commandos stormed the Oasis residential compound, which houses company executives.
In all, 22 people were killed. Thirteen people were gunned down on Saturday, and nine hostages were killed after they reportedly tried to escape during the night.
UK warns of more attacks
A staff member from the compound has relayed an account from a freed hostage who said a deal was done in which the gunmen were allowed to escape in exchange for not blowing up the building.
That version of events has not been confirmed, but BBC Middle East correspondent Paul Wood says questions are being asked about exactly what did happen.
The Saudi ambassador to Britain, Prince Turki al-Faisal, has rejected any idea of collusion between the attackers and the security forces and insisted the authorities were fighting terror groups using all means available.
1. Al-Khobar Petroleum Centre: Four gunmen arrive at 0715 Saturday, shoot at guards, enter building and fire at employees.
2. Arab Petroleum Investments Corp: Gunmen shoot British employee dead in his car at gate.
3. Oasis compound: Gunmen enter compound and take about 50 people hostage on sixth floor of hotel building. At 0530 on Sunday, Saudi forces land on roof and storm building. Nine hostages are found dead, 41 are released. Three militants escape, one is arrested.
He told the BBC's Today programme that the attackers go for the softest targets and if they really did have helpers in positions of authority they would be able to attack much more high-profile targets.
Security sources said a car the militants used to escape had been found abandoned on the outskirts of the nearby city of Dammam.
The UK ambassador to Saudi Arabia has warned that more attacks are likely.
Sherard Cowper Coles said there was no intelligence about specific threats, but that a picture was emerging of scores of militants actively planning attacks of the kind seen in Khobar.
Britain is advising against all but essential travel to Saudi Arabia, but has not yet followed the US in telling its citizens to leave.
An audiotape posted on an Islamic website claimed the attack for al-Qaeda. "We will cleanse the Arabian peninsula of infidels," the tape said.
The Saudi Interior Ministry says the foreigners who were killed came from Britain, Egypt, India, Italy, the Philippines, South Africa, Sri Lanka, Sweden, and the US.
It said 25 people of different nationalities were wounded.