BAGHDAD , Iraq -LRB- CNN -RRB- -- Court proceedings in the trial against Tariq Aziz , one of the best-known faces of Saddam Hussein 's former regime in Iraq , and several co-defendants have ended after being in session only briefly Tuesday . The trial of Tariq Aziz , pictured here in a Baghdad courtroom in July 2004 , has begun . The trial , which is to resume May 20 , was delayed because one of the defendants , Ali Hassan al-Majeed , also known as `` Chemical Ali , '' was not present because he was ill . Iraqi procedural codes require that all defendants be in court for the first session . Chief Judge Raouf Abdul Rahman read a U.S. medical report signed by three doctors that said al-Majeed is in critical condition after suffering a heart attack two weeks ago . He has been released from the hospital but still requires daily treatment and doctor visits . The report said that traveling to court from his detention facility could worsen his health . He can not walk up stairs or sit in court for long hours , it said . He will need three weeks to recover and may need some sort of surgery , the report said . It added he is diabetic and suffers from `` acute heart failure . '' Treatment includes clearing of the arteries followed by either open heart surgery or stents in the arteries , but neither option is available at this time , the report said . Ali Hasan al-Majeed , who was a top Baathist official during the Saddam Hussein era , is awaiting execution after being convicted of genocide in connection with the killing of Kurds during the Anfal campaign in the late 1980s . Aziz , al-Majeed and six others are now facing trial for having a role in the execution of 42 Iraqi merchants in 1992 . A former deputy prime minister , Aziz was the first to be called into court , followed by six other defendants . Aziz appeared frail , walked slowly with a cane , and was coughing and blowing his nose . He was sitting in the seat Saddam Hussein used during his appearances in court and was represented by a private attorney . The court was sorting out which defendants did not have attorneys present . This is the fourth major trial of former Hussein regime officials since his government was overthrown . The most prominent was the 2006 trial that led to the execution of Hussein and three lieutenants for a crackdown in the Shiite town of Dujail in which more than 140 men allegedly plotting Hussein 's assassination were executed . Aziz 's lead attorney , Badie Aref -- who was an attorney for Hussein in that trial -- is charged with contempt of court in Iraq and has been in Jordan since a warrant for his arrest was issued last year . He said he would return to Baghdad for this trial only if he were assured he would not be arrested . Meanwhile , amid a swirling , blanketing sandstorm , fierce fighting in Baghdad Tuesday saw U.S. troops kill 32 `` enemy forces '' in a gunbattle , according to the U.S. military . Iraqi authorities reported 16 people were killed in a residential area in the same clash . The Iraqi Interior Ministry said the fighting was in the predominantly Shiite Sadr City neighborhood in eastern Baghdad . Five suspected insurgents dressed in Iraqi army uniforms attacked the home of a human rights worker in Diyala on Tuesday , killing the resident of the home and an Iraqi soldier who lived in the neighborhood , according to the U.S. military . Two Iraqi civilians also were injured in the small-arms attack . `` Attacking civilians in their homes is both criminal and barbaric , '' said Major Peggy Kageleiry , spokeswoman for the military 's Multi-National Division - North . Insurgents have been attempting to exploit the harsh conditions , which have curtailed flights coming into Baghdad International Airport . Sandstorms make it easier for militants to screen their activities and harder for U.S. air power to be deployed effectively . A U.S. military spokesman said fighting began around 9:30 a.m. when militants fired at a U.S. patrol and wounded an American soldier . When the soldier was being evacuated , a U.S. vehicle was struck by two roadside bombs and peppered with small-arms fire and rocket propelled grenades . That left two more soldiers injured . Three more soldiers were wounded in the fighting . Soldiers used a `` combination of weapon systems available , including a guided multiple launch rocket -LRB- GMLR -RRB- system '' to fight the insurgents and killed at least 28 militants in a four-hour long battle , the military said . Lt. Col. Steven Stover , spokesman for Multi-National Division-Baghdad , said three GMLRs were launched , at 11:23 a.m. , 1:03 p.m. and 1:37 p.m. Officials with Iraq 's Interior and Health Ministry told CNN 16 people were killed and 45 people were wounded when U.S. rockets hit at least three houses in a residential area in Sadr City around 1:15 p.m. Two children and a woman were among the dead and four children and five women were among the wounded , they said . Asked if he was aware of reports of civilian casualties from the strikes , Stover said , `` If there were civilian casualties , I sincerely regret them . `` The rockets struck militants firing from buildings , alleyways and rooftops . It was these militants who initiated the engagement by attacking U.S. soldiers . Our soldiers have a right to defend ourselves . '' Two U.S. soldiers were killed Tuesday in separate incidents in northwest Baghdad , the military said . The first soldier died from wounds suffered from insurgent small-arms fire at about 8:50 p.m. local time in northwest Baghdad , according to a U.S. military public affairs office . The second soldier died at about 10:15 p.m. when the vehicle he was riding in was struck by an improvised explosive device . The names of both soldiers were being withheld until their families could be notified . E-mail to a friend CNN 's Jomana Karadsheh , Christine Theodorou , Mohammed Tawfeeq and Ingrid Formanek contributed to this report .