Police in the Pakistani city of Karachi say a suicide bomber killed at least 25 people in an attack on a Shia Muslim procession.
About 60 others were injured in the attack on MA Jinnah road, one of the city's main thoroughfares. Survivors were left stunned.
The explosion sent a plume of black smoke into the sky over the city.
Some of the marchers who survived the bombing then attacked security forces and ambulance workers. Gun shots were heard.
A number of vehicles were set on fire and shops and other property damaged, bringing appeals for calm.
Dozens of wounded marchers were helped to ambulances for treatment. Security forces are on high alert for the holy month of Muharram or Ashura.
The ceremonies mark the death in battle of Imam Hussein, grandson of the Prophet Muhammad, in the year 680.
Thousands of people had been taking part in the procession in Karachi when it was attacked.
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