BAGHDAD, Iraq (CNN) -- Two mortars were fired Monday into Baghdad's heavily fortified International Zone where U.S. and Iraqi offices are based, Iraqi Interior Ministry officials told CNN. There was no word on casualties or damage.
At least 12 mortars were fired at the International Zone on Sunday, according to the U.S. military.
Violence flared across Baghdad as two Iraqi government employees were killed in roadside bombings and at least one civilian was killed in a suicide bombing aimed at a pro-U.S. militia checkpoint.
Coalition forces killed 10 members of al Qaeda in Iraq -- believed to be tied to suicide bombings -- and detained one suspect during an anti-terror sting outside Baghdad, the U.S. military said.
They also detained four other al Qaeda suspects in operations in and around Baghdad, including three in Abu Ghraib -- about 20 miles west of the capital.
The deaths follow a volatile Sunday in Iraq's capital, when fighting and attacks killed at least 45 people, including 38 insurgents during battles in the eastern sector of the city.
The violence in eastern Baghdad is a continuation of month-long hostilities between American and Iraqi troops and Shiite militants, labeled "criminals" and "evildoers" in U.S. military releases.
While the U.S. military says it is not fighting a particular group, Iraqi officials say much of the fighting in the region has involved elements of the Mehdi Army loyal to Muqtada al-Sadr.
Four U.S. soldiers were killed in Iraq Monday by indirect fire, the U.S. military said. The deaths bring the number of U.S. military personnel killed in the Iraq war to 4,055, 150 of them in 2008.
Monday's suicide bombing, in eastern Baghdad, was conducted with a motorcycle and targeted a checkpoint manned by the Sons of Iraq, the American-backed militia group. Two of those wounded are members of the group.
At least one person was killed and four were wounded when a roadside bomb struck a pickup truck in central Baghdad. The casualties were employees of the Ministry of Electricity. In eastern Baghdad, a roadside bomb struck a Ministry of Health minibus, killing one employee and wounding two.
Ministry officials reported other incidents in Baghdad on Monday.
• Eight mortar rounds hit the Jazaer police station, also a Joint Security Station, in eastern Baghdad. Ten police were wounded and the building was damaged in the incident, which occurred in or bordering Sadr City. Watch video of destruction in Sadr City. »
• At least three members of a Sons of Iraq group were wounded Monday afternoon when a bomb exploded near a restaurant in the predominantly Sunni neighborhood of Adhamiya in northern Baghdad.
• Two civilians were wounded when a mortar round slammed into their house in western Baghdad's Mansour district.
• At least five civilians, including a child, were wounded when a mortar hit a residential compound bordering the International Zone.
• At least three Iraqi civilians were wounded when a mortar fell on Abu Nawas Street in central Baghdad, across the Tigris River from the International Zone.
• A Katyusha rocket landed in the front garden of the Sadeer Hotel in central Baghdad. There were no casualties.
• A roadside bomb targeting a U.S. military convoy in western Baghdad's Amil neighborhood wounded at least two civilians and struck a water pipeline.
• The Serbian government has forgiven all $3 billion in debt owed it by Iraq's former regime, Iraq's Ministry of Defense said Monday. Two weeks ago, Iraq negotiated a multimillion-dollar arms deal with Serbia. E-mail to a friend
CNN's Christine Theodorou and Jomana Karadsheh contributed to this report.