Saudi security forces raided a house in northern Riyadh late on Wednesday night and killed seven people suspected of involvement in two car bomb attacks in the capital.
Police chased the seven fighters in the northern districts of Maseef and Taawun, a security source said.
"The militants fled to a villa in the Taawun district, which was stormed by security forces who killed the seven," he added.
A car bomb had earlier exploded near the interior ministry, followed by a similar attack outside a security camp.
There was no immediate word about casualties.
Witnesses reported hearing two large blasts near the ministry building as well as gunfire. The blasts were felt up to 2km away, they said.
A few minutes later, a second car bomb exploded outside a camp for special security forces in the city after attempting to crash into the base, sparking a shootout with guards, sources said.
Earlier in the day, Saudi police killed a suspected opposition fighter in a shootout in Riyadh and captured two wanted men after a gun battle in the Red Sea city of Jedda, state television and security sources said.
It is not clear if the men were on the list of 26 most wanted al-Qaida fighters.
Saudi Arabia, the world's largest oil exporter, has been battling a wave of opposition attacks since May 2003, in which about 170 people have been killed, including Westerners.
Earlier this month, al-Qaida fighters stormed the US consulate in Jedda, killing five non-American staff in the first attack on a Western mission in Saudi.
Bin Ladin has called for attacks
on oil facilities in the kingdom
An audio tape attributed to Saudi-born al-Qaida leader Usama bin Ladin praised the attack, in which four fighters were killed, and called for strikes on oil facilities in the kingdom.
Opponents of the ruling House of Saud say it is dictatorial and corrupt.
But the Saudi government accuses its opponents of "terrorism" and the desire to provoke instability in the country.