A suicide bomber targeted a Shia procession in Pakistan's commercial capital Karachi, killing at least 30 people and injuring over 60 others.
The provincial health minister said 'we have declared an emergency at all hospitals in Karachi and doctors are making every effort to save the injured. The situation is very grim.'
Two suspects were arrested at the bomb site.
The blast sparked riots in Karachi where angry mourners threw stones at ambulances, torched cars and shops and fired bullets into the air.
Pakistan has deployed tens of thousands of police and paramilitary forces, fearing sectarian clashes or militant attacks on Ashura processions.
Ashura falls on the 10th day of a 40-day mourning period during the Islamic calendar's first month, Moharram, which commemorates the death of Imam Hussein, a grandson of the Prophet Mohammad, who was killed in battle in AD 680 in the Iraqi city of Kerbala.
Processions by minority Shia are often attacked by majority Sunni Muslim militants.
Militant attacks have killed more than 2,760 people since July 2007, according to official figures.
