BAGHDAD (Agencies) -- At least 32 people were killed and 28 others wounded Saturday when a suicide bomber stepped onto a bus carrying Shia pilgrims in Iraq and detonated himself, police and interior ministry officials said.

The attack -- which occurred between Baghdad and Samarra -- was the second targeting pilgrims in the last three days. Most of the casualties were Shiite pilgrims heading back south to Nasiriya from Samarra in the north, CNN reported.
They made the trip to commemorate the martyrdom of Imam Hassan al-Askri (AS).
On Thursday, a suicide bomber drove into a rest tent for Shia pilgrims north of Baghdad, killing eight people and injuring 30 others, police said.
“The suicide bomber quickly ran into the bus when it stopped at a checkpoint several kilometers (miles) outside Samarra, and detonated his vest inside the vehicle,” a police official said.
“The latest death toll is 30 wounded, among them two women, and 28 wounded, among them also two women,” said a medical source at Samarra General Hospital.
“All of the victims inside the bus were Iraqi pilgrims, and casualties included people outside the bus as well,” said an ambulance driver who ferried the victims to hospital.
It was the deadliest single attack in Iraq since a January 27 car bomb ripped through a funeral ceremony in a Shia district of Baghdad, killing 48 people, AFP reported.
Samarra, 110 kilometers (70 miles) north of Baghdad, houses the gold-domed shrine of revered ninth century Imam Hassan al-Askari (AS) which draws pilgrims from Iraq and round the world.
Saturday marked the annual commemoration of his martyrdom.
A car bomb ripped through a procession of pilgrims heading for the shrine on Thursday on the outskirts of the town of Dujail farther south, killing at least nine pilgrims and wounding 39, a provincial spokesman said.
Tens of thousands of people died in violence sparked by the destruction of the Askari shrine's gold dome five years ago by suspected Sunni extremists loyal to Al-Qaeda.
The mosque itself was built in 944, and the golden dome was added in 1905.
Although violence has fallen in Iraq since its peak in 2006 and 2007, attacks remain common.
January was the deadliest month since last September, according to official figures. A two-week surge in violence last month shattered a relative calm in the country.
Data compiled by the ministries of health, defense and interior showed that a total of 259 people -- 159 civilians, 55 policemen and 45 soldiers -- were killed in violence last month.
That figure was the highest since September 2010, when 273 people died.
Prime Minister Nuri al-Maliki has blamed attacks against Shia on “takfiris,” an Islamic term for extremists but used by the premier to mean anti-Shia Al-Qaeda militants.
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