RIYADH — The authorities are carrying out an investigation into a drive-by shooting in Riyadh in which two Saudi policemen were killed early Wednesday, Riyadh Police spokesman said. Policemen Thamer Amran Al-Mutairi and Abdulmohsen Khalaf Al-Mutairi were patrolling in their vehicle at 1:30 a.m. when they were shot. The pre-dawn attack came in an eastern district of the capital, the police spokesman said in a statement carried by the Saudi Press Agency. “A security patrol was carrying out its duties in east Riyadh when it came under fire from an unidentified vehicle,” the spokesman said. On March 29, two policemen were wounded in a similar attack in Riyadh. On March 22, the United States resumed consular services in the Kingdom following a week-long closure over unspecified “heightened security concerns.” In January, three guards, including a commander, were killed in a desert area near the Iraqi border. No group has claimed responsibility for that attack. Saudi security forces have also come under occasional attack in the Eastern Province. But attacks on police are rare in the capital. Westerners have been attacked in Saudi Arabia four times since October, including drive-by shooting that wounded a Danish national in Riyadh on Nov. 22.