BAGHDAD , Iraq -LRB- CNN -RRB- -- Three U.S. soldiers were killed and 31 others wounded in two rocket attacks Sunday afternoon in Baghdad , the U.S. military said . Mehdi Army militiamen celebrate after attacking an Iraqi Army vehicle in Baghdad 's Sadr City on Sunday . Earlier Sunday , fighting between U.S. troops and the Mehdi Army militia loyal to Shiite cleric Muqtada al-Sadr left at least 20 dead and 52 wounded in Baghdad 's Sadr City , according to an Iraqi Interior Ministry official . The U.S. military said it had no information about the Sadr City fighting . Sunday 's violence came as Iraqi Prime Minister Nuri al-Maliki demanded al-Sadr disband his Mehdi Army and threatened to bar al-Sadr 's followers from the political process if the cleric refused . Watch a report from the front line in Sadr City '' `` A decision was taken yesterday that they no longer have a right to participate in the political process or take part in the upcoming elections unless they end the Mehdi Army , '' al-Maliki said . Sunday 's American fatalities bring the death toll of U.S. troops in the Iraq war to 4,022 ; that toll includes eight civilian contractors working for the Pentagon . Nearly 30,000 others have been wounded in action . An attack involving a `` couple of rounds '' of fire on the International Zone , also known as the Green Zone , killed two soldiers and wounded 17 others about 3:30 p.m. , a military official said , declining to give the specific location of the attack for security reasons . A separate attack about 30 minutes earlier killed one soldier and wounded 14 at a U.S. military outpost in Rustamiya in southeastern Baghdad , the military said . Responding to al-Maliki 's comments , a spokesman for al-Sadr , Sheikh Salah al-Obeidi , said that any effort to bar Sadrists from participation in politics would be unconstitutional -- and that any decision to disband the Mehdi Army is not the government 's to make . `` It is up to the side that established it , '' he said . Al-Maliki spoke in an exclusive interview with CNN after a weeklong military offensive against what Iraqi officials called gangs and militia members in the southern Iraqi city of Basra . Hundreds were killed or wounded in the fighting across Iraq , which reportedly ended when Iranian and Iraqi Shiite officials held talks in Iran with al-Sadr . Asked about Iran 's role in ending the Basra conflict , al-Maliki attributed the cease-fire to the work of his security forces . Haidar al-Abadi , an Iraqi lawmaker who belongs to al-Maliki 's Dawa Party , said last week that Iranian officials participated in the discussions , and another source close to the talks said the Iranians pressured al-Sadr to craft an agreement . `` I am not aware of such an attempt , '' al-Maliki said Sunday . `` What happened on the ground and the breakdown in the structure of this militia is what made Muqtada al-Sadr issue his statement to withdraw his militants from the streets . What happened was something to save Muqtada , not to help us . '' Watch al-Maliki talk about issues that concern Iraq '' In northern Iraq , security forces detained a suspect Sunday and were searching for others in connection with the kidnapping of 42 college students , authorities said . Gunmen seized the male students in northern Iraq before releasing them several hours later , according to a military spokesman and police in Nineveh province . None was harmed , according to the U.S. military . Gunmen stopped two buses loaded with students who were on their way to college , but one bus managed to escape , police said . Four students on the bus that escaped were wounded by gunfire , police said . Students on the other bus were released Sunday afternoon after coalition military forces spotted the bus during an air patrol on the western outskirts of Mosul , according to a U.S. military news release . The kidnappers fled the vehicle after it was stopped , according to a military press release . Other developments • A Christian priest was shot and killed in eastern Baghdad 's Wihda neighborhood around noon Saturday , according to an Iraqi Interior Ministry official . The priest was identified as Father Yousif Adel . He belonged to St. Peter and Paul 's Assyrian Orthodox Church . • At least two people were killed Saturday and 16 others wounded when a bomb exploded in a minibus in eastern Baghdad 's Beirut Square , the official said . • President Bush is planning to address the nation Thursday morning about the Iraq war , sources said . Bush is expected to address the administration 's decision to reduce combat tours of duty from 15 months to 12 months , Republican and Democratic sources said . E-mail to a friend CNN 's Nic Robertson , Jomana Karadsheh and Ingrid Formanek contributed to this report .