Interior Ministry spokesman Maj. Gen. Mansour al-Turki said in a statement that four masked men on motorcycles threw the firebomb at a station in the Awamiya neighborhood of Qatif late Friday night. Police killed one and the rest fled.
He said that in a nearby district, Sihat, masked attackers on motorcycles fired at two security patrols, wounding four. It was not clear if the attackers were the same group.
Shiites, who make up 10 percent of the kingdom's population and are concentrated in the oil-rich east, have staged frequent demonstrations against Saudi Arabia's Sunni rulers in the last year.