BAGHDAD – U.S. and Iraqi forces blocked access to a town on the northeast outskirts of Baghdad where Shiite gunmen were dug in for a third day Monday behind earthen barriers. Police issued calls for residents to leave the town, and some said they were running out of food and fuel.

The blockade of Husseiniyah came as at least 16 people died when four car bombs rocked the center of the capital. Three of the blasts took place in one 30-minute span, as the relentless Baghdad summer sun pushed temperatures to 115 degrees.

Police, morgue and hospital officials reported a total of at least 59 people killed or found dead nationwide, and the American military announced the deaths of three soldiers and a Marine. At least 3,636 members of the U.S. military have died since the Iraq war began in March 2003, according to an Associated Press count.

The continued fighting and deaths of Iraqis and American forces in the sixth month of the American bid to calm Baghdad and the center of the country illuminate the stubborn resistance to a political solution in Iraq, where the government and legislature appear determined to press for sectarian advantage rather than Iraqi unity.

The Shiite-dominated parliament said Prime Minister Nouri al-Maliki should intervene to end the crackdown by U.S. and Iraqi forces on Husseiniyah. The town is a stronghold of the Mahdi Army, the militia loyal to radical cleric Muqtada al-Sadr, and straddles the highway to Baqouba, where U.S. forces are in the second month of a drive to cleanse that region of al-Qaida in Iraq.

State-run Iraqiya television said the Husseiniyah blockade “would have serious consequences on people’s lives there.”

A 51-year-old woman resident, who would give her name only as Um Bassem, said police, apparently expecting a major outbreak of fighting, had issued calls for residents to leave Husseiniyah if they could.

“My husband offered to take us out and return to protect our house and belongings, but we refused to leave because we would be so worried about him,” Um Bassem told an AP reporter in the area. She said food stocks were becoming low.

“We decided to stay home in two rooms at the back of the house. We can’t leave because we have valuable things and we fear looters,” she said.

Lt. Col. Michael Donnelly, spokesman for U.S. forces north of Baghdad, said American and Iraqi forces were now allowing “commercial vendors to bring food to the south of Husseiniyah. Civilians are authorized to walk to these vendors to buy food. Donkey carts may be used, but no vehicle movement is authorized. We are also allowing civilians that need medical aid, to walk to the Hamid Shaub Hospital for free treatment.”

Trouble broke out in Husseiniyah when U.S. forces took small arms fire shortly before midnight Friday and ordered an airstrike on the building from which the gunmen were shooting. The military said helicopters fired missiles at the building and three gunmen fled to a second building.

U.S. aircraft then bombed the second structure, setting off at least seven secondary blasts believed caused by explosives and munitions stored inside the building, the military said, adding that Iraqi police told American forces six militants were killed and five wounded.

The military account contradicted reports from Iraqi police and hospital officials contacted by The Associated Press. Those officials said 18 civilians had been killed and 21 wounded in the attacks at 2 a.m. Saturday.

AP Television News videotape showed wounded women and children lying in hospital beds, and white pickup trucks carrying at least 11 bodies wrapped in blankets to the morgue. Men unloaded the bodies, including several that were small and apparently children.

Relatives said the dead were killed in the airstrike. The conflicting accounts could not be reconciled.

Donnelly said militant gunmen “are using civilians as protection and have no regard for the innocent.

“Currently there are berms (earthen barriers) placed to impede movement to/from the city by the militia group, who have fired on CF (Coalition Forces) over the past day(s). The intent of these berms remains unclear, but it is impeding movement in and out of the town for sure,” he said in response to an e-mail asking for details.

In Karradah, a predominantly Shiite district in central Baghdad, two of four car bombs exploded nearly simultaneously. A third hit about 30 minutes later. Police officials, who spoke on condition of anonymity because they were not authorized to talk to reporters, said at least 16 people, including five policemen, were killed.

Karradah, an upscale shopping and residential district, has suffered repeated high-profile bombings, and Monday’s attacks occurred despite a five-month-old U.S.-Iraqi security operation aimed at clamping off violence in the capital.

Hassan Sami, a 28-year-old clothing store owner in Karradah, said he was showered by shattered glass that wounded his left arm.

“Nothing was left except the smell of charred flesh mixed with gun powder and wreckage stained with blood,” Sami said. “We’ve been attacked many times before, and the government can’t do anything for this area. It only sends its patrols who roam the streets with their annoying sirens without doing anything useful.”

Iran’s ambassador to Baghdad, meanwhile, confirmed that the United States and Iran will discuss the security situation in Iraq on Tuesday in Baghdad, the official Islamic Republic News Agency reported.

“The composition of the negotiating teams will include ambassadors of Iran and America in Baghdad, as head of the two teams, with observance of Iraqi officials,” IRNA quoted Hasan Kazemi Qomi as saying Monday.

The time and place of the second meeting between U.S. Ambassador Ryan Crocker and Qomi have not been disclosed.