Suicide bombers killed 50 police recruits in central Iraq and 49 Shi'ite pilgrims in the south Thursday, a stepped-up attack as politicians worked to form a coalition government. Five US soldiers were killed by a roadside bomb. The two-day death toll from attacks rose to 163, a surge of violence not seen since before the December 15 parliamentary elections. Iraq's prime minister denounced the violence as an attempt to derail the political process. The country's mainstream political parties hope a new, broad-based government will weaken the insurgency. A statement from the US military said only that the soldiers were patrolling in the Baghdad area. But Iraqi police Capt. Rahim Slaho said a US convoy headed for the Shi'ite holy city of Karbala had been attacked 35 kilometers (15 miles) south of the city and that five soldiers were killed. No names were released pending notification of family members. The suicide blast Thursday near the Imam Hussein shrine in central Karbala, 80 kilometers (50 miles) south of Baghdad, killed 49 people and injured 52, Karbala police Col. Razaq al-Taie. In the attack's aftermath, a woman and an infant girl in a bright red jumpsuit lay in a pool of blood, their faces covered by a sheet. Television images showed men ferrying the wounded in pushcarts. The bomber appeared to have set off the explosion only about 30 meters (30 yards) from the shrine in a busy pedestrian area surrounded by shops. In Ramadi, a US spokesman said about 30 people were killed when a suicide bomber attacked a line of about 1,000 police recruits. Iraqi police said about 40 people were injured. The attack took place at a police screening center in Ramadi, an insurgent stronghold 115 kilometers (70 miles) west of Baghdad. Marine Capt. Jeffrey S. Pool said recruits later got back in line to continue the screening process. In other violence Thursday, a suicide car bomb killed three Iraqi soldiers in Baghdad, Lt. Col. Thamir al-Gharawi said, and gunmen killed three people in separate incidents, police said, raising the death toll Thursday to 110. Attackers killed 53 people on Wednesday. The Karbala bomber detonated a vest with about eight kilograms (17.5 pounds) of explosives and several hand grenades, al-Taie said. Small steel balls that had been packed into the suicide vest were found at the site, as was one unexploded grenade, he said. A statement by the Supreme Council for the Islamic Revolution in Iraq, or SCIRI, a partner in the governing Shi'ite coalition, said the attacks are part of a plot "to eliminate the Shi'ites in Iraq." "These crimes took place after statements and threats of a civil war issued by some Iraq political groups," it said. "Such political groups bear the responsibility for every blood drop that was shed." Final results from the elections should be released within two weeks, and are expected to show the United Iraqi Alliance with about 130 of parliament's 275 seats. That figure is well short of the 184 needed to form a government.