BAGHDAD - Militants accidentally set off their own car bomb Monday at a training camp in the countryside north of Baghdad, leaving 21 dead and resulting in two dozen arrests, Iraqi officials said.
In the city of Mosul to the north, meanwhile, the speaker of parliament -- one of the most prominent Sunni officials in Iraq -- escaped unhurt from a roadside bomb attack on his motorcade.
Car bombs are one of the deadliest weapons used by the al-Qaida breakaway group in Iraq that dominates the Sunni insurgency in Iraq, with coordinated waves of explosions regularly leaving scores dead in Baghdad and elsewhere across the country.
The bombs are sometimes assembled in farm compounds where militants can gather without being spotted, or in car workshops in industrial areas. Police say the camp outside Samarra, a Sunni city 95 kilometers (60 miles) north of Baghdad, was in an orchard in the village of al-Jalam.
A police officer said the militants were attending a lesson on making car bombs and explosive belts when a glitch set off one of the devices.
The officer said security forces rushed to the area after hearing the sound of the explosion. They arrested 12 wounded suspected militants plus another 10 trying to flee the area.
Security forces found seven car bombs, several explosive belts and roadside bombs after searching two houses and a garage in the orchard, he said.
Meanwhile, authorities in the northern city of Mosul said that parliamentary speaker Osama al-Nujaifi escaped an assassination attempt that left one bodyguard wounded.
Police officials said a roadside bomb went off next to the motorcade. Al-Nujaifi was not hurt in the attack.
Medical officials confirmed the casualties. All officials spoke anonymously because they were not authorized to speak to media.
Violence has spiked in Iraq since April of last year, when security forces cracked down on a Sunni protest camp.