BAGHDAD — A blast at a military base north of Baghdad killed more than two dozen people Tuesday, but there were conflicting accounts of what caused the explosion.

A police official said a car bomb exploded in a parking lot near a recruitment center at the base, in Taji, 12 miles north of Baghdad, but an Iraqi army source said a suicide bomber mingled with a crowd at the gate.

Medical officials at the Kadhimiya hospital near the recruitment center said more than 30 people were wounded, most of them seriously, and the death toll of 26 was likely to rise. The Associated Press put the death toll at 32 and said a suicide bomber driving a car packed with explosives had attacked as soldiers changed shift, with many military personnel walking to and from minibuses in the parking lot.

Mohamed Talal was among the would-be recruits at the base. Reached by telephone, he said the crowd of applicants had been told to check their names against lists posted on the walls outside.

“I was heading to the place near the parking lot to check my name when all of sudden a strong explosion happened where the people was gathering,” Talal said. “I turned and started to run, and I began to feel shrapnel in my back, and I fell to the ground.”

Security forces cordoned off the area and mounted raids and searches nearby.

The bombing was the second in Taji in as many days. On Monday when a car bomb injured eight members of an army patrol.

While violence is generally lower than at the height of Iraq’s insurgency, assailants regularly attack Iraq’s security forces to erode confidence in the government’s ability to maintain order.

Separately, in the Dora neighborhood of southern Baghdad, gunmen attacked a police checkpoint Tuesday, killing one policeman and wounding two others.