Nine suspected terrorists and a bystander died after militants launched co-ordinated car bombings and battled security forces in the Saudi capital Riyadh.
Oil prices jumped after the attacks in Riyadh, signalling that Islamic extremists were keeping up their fight, despite the kingdom's crackdown on al-Qaeda.
Police said the hunt for suspects in yesterday's strikes continued today.
The Interior Ministry blamed the assaults on a "deviant group" - the government's term for al-Qaeda.
Police said two militants detonated a car bomb inside a traffic tunnel by remote control. Saudi TV reported a bystander, a limousine driver, was killed.
The Interior Ministry, in a statement on state television, said five security agents and a few bystanders were injured, none seriously, and reported no deaths.
The attackers who set off the ministry blast then fled and fought police in northern Riyadh in a gun battle that killed seven militants and injured an unspecified number of officers, police said.
The blast rocked the ministry building and shattered windows al around. In addition to the Interior Ministry, the neighbourhood, known as al-Murabaa, includes the Civil Service Ministry, a post office and a luxury hotel.
The Interior Ministry, a massive, modern high-rise, was shown with its windows brightly lit and few signs of damage in pictures broadcast by Saudi television. Damaged cars, including a blood-splattered taxi, sat outside.
Half an hour after the first blast and five miles away, a second explosion went off at a recruiting centre for security troops. Police said two suicide bombers tried to storm the centre but blew up their car prematurely after police fired on them. The two bombers were killed, and the Interior Ministry said 12 security officers inside the centre and an unspecified number of bystanders were slightly injured.
The bombings came late in the evening, when few people would have been in the government buildings.
Previous attacks seemed designed to maximise casualties, often Arab and Muslim. A night-time attack focused on targets associated with Saudi security forces could have been meant to underline militants' opposition to the government and avoid criticism that the extremists did not value Arab and Muslim lives.
Oil prices rose more than four per cent yesterday in New York, with analysts citing fears of instability in Saudi Arabia, which has the world's largest oil reserves.
AP