Two suspected al-Qaeda militants and a police officer have been killed in a clash at a checkpoint in Saudi Arabia, near the Yemeni border, officials say.
Shots were fired after a female police officer approached a car to check the identities of the three people inside - two of whom were disguised as women.
The two dead men were wearing explosive vests. A third man was arrested.
It was the first known armed clash between suspected al-Qaeda militants and troops in the kingdom since August.
Al-Qaeda in the Arabian Peninsula is said to have been behind the suicide bombing in the port of Jeddah at the end of the month which injured Assistant Interior Minister Prince Mohammed bin Nayef.
The attack came weeks after the arrest in Saudi Arabia of 44 suspected members of the group, which is aligned with Osama Bin Laden's international network and led by a former associate.
Tuesday's clash happened at a police checkpoint about 120km (75 miles) from the city of Jizan, on the road to Asir province, the interior ministry said.
Ministry spokesman Brig Gen Mansour al-Turki said the vehicle in which the three suspected militants were travelling had been about to undergo a security check on the basis of "information on the planning of terrorist acts by the deviant minority" when started shooting at the security forces.
Al-Qaeda in the Arabian Peninsula says it was behind August's bombing in Jeddah
He said the subsequent exchange of fire resulted in "the deaths of two passengers in the vehicle and the arrest of a third".
The two men wearing women's clothing had explosive vests and grenades underneath, and "more grenades, automatic weapons and bomb-making materials" were found inside their car, he added.
Gen Turki said one police officer was killed and another wounded in the incident. It is not known if the policewoman was one of them.
The Saudi Arabian government is concerned about the resurgence of Al-Qaeda in the Arabian Peninsula in Yemen, where the authorities have been ineffective in cracking down on the group, focusing instead on fighting Shia rebels.
Last month, the director of the US National Counter-terrorism Centre, Michael Leiter, told a Senate hearing that the group had gained a dangerous foothold across the border.
"We have witnessed the re-emergence of al-Qaeda in the Arabian Peninsula, with Yemen as a key battleground and potential regional base of operations from which al-Qaeda can plan attacks, train recruits and facilitate the movement of operatives," he said.