The series of bomb attacks in the Saudi capital Riyadh on Monday were all targeted at luxury compounds housing foreign nationals.
Blasts were reported at four compounds in Riyadh
Three blasts were reported in quick succession at about 2330 local time.
Buildings in the Al-Hamra compound, in the Gharnata district of the city, were badly damaged in what appeared to be a co-ordinated attack involving car bombs and gunmen.
Some witnesses reported that the attackers apparently began their assault when guards opened a security gate to let another vehicle leave.
A security official told the Associated Press that a black Chevrolet car crashed into a residential housing block in al-Hamra.
At the separate Vinnell compound, a residential block housing defence workers was "very seriously damaged", according to US ambassador to Saudi Arabia Robert Jordan.
The third compound, in the Cordoba district of the city, was less seriously damaged as the bomb exploded at the gate rather than inside the premises.