BAGHDAD — American troops killed the Qaeda mastermind of the latest bombing at a prized Shiite shrine, and at least 13 people died when mortars rained down on their Baghdad neighborhood, officials said yesterday.

Haitham Sabah Shaker Mohammed al-Badri was the Qaeda in Iraq emir of Salahuddin province, and the figure responsible for the June 13 bombing of the twin minarets at the Golden Dome mosque in Samarra, the American military said in a statement. He died in an American operation east of Samarra on Thursday, though his death was announced three days later.

“Al-Badri was positively identified by close associates and family members,” the statement said.

Badri had also been a suspect in an earlier bombing, in February 2006, which destroyed the same mosque’s golden dome and set in motion an unrelenting cycle of retaliatory sectarian bloodletting. Thirteen people were killed early yesterday morning and 14 wounded by mortar shells in southeast Baghdad, police said.

At least three mortars hit the Shiite-dominated Mashtal area in southeast Baghdad, a police officer said on condition of anonymity out of security concerns. It was unclear whether they were aimed at the area, or whether the shells fell short of their intended targeted.

Mashtal’s main intersection, where the gas station is located, leads to other Shiite slums such as Kamaliyah, Fudailiyah, and Sadr City.

Police and witnesses said two of the mortar shells landed near a gas station where people were lining up for fuel at the start of the work week. Many of the victims were burned by fuel that burst into flames from the attack, the officer said.

AP Television News footage showed at least two cars with their windshields and windows shattered. The tail fin of a mortar shell was lodged in the ground nearby. Pools of blood soaked into the dusty ground outside crude cement block homes.

“Shrapnel hit my front window… then two explosions took place,” said minibus driver Ali Abdul-Karim, 28. “Me and other drivers ran fast toward the sound of the explosions, to help evacuate the victims.”

Mr. Abdul-Karim described a ghastly scene, with rescuers scurrying to discern the wounded from the dead.

“I saw two elderly women bleeding and laying on the ground. I don’t know whether they were injured or dead,” he said. “I also saw three seriously wounded boys laying near their jerry cans. A man was running and screaming, with his hands on his belly, which was cut by shrapnel.”

The wounded lay bandaged on gurneys at a nearby hospital. Male relatives of the victims, many in clothes stained with their loved ones’ blood, milled around outside the neighboring morgue, where at least eleven bodies were visible on metal shelves.

The Golden Dome — or Askariya — shrine in Samarra, 60 miles north of Baghdad, is one of the holiest places for Shiites. Despite heightened security put in place after the February 2006 bombing, suspected Al Qaeda militants managed to infiltrate the compound and bring down its two minarets in June.

The first attack unleashed a bloodbath of reprisals — of Shiite death-squad murders of Sunnis, and Sunni bombing attacks on Shiites. At least 34,000 civilians died in last year’s violence, the United Nations reported.

The second bombing, in June, toppled the two minarets — which for many Shiites, were symbols of resilience in the face of a tireless Sunni insurgency — and dealt a bold blow to hopes for reconciliation.

Also yesterday, the American military announced the capture of three more suspected insurgents in raids two days earlier in the Samarra area.