There are fears the death toll will rise further
More than 30 people have been killed and dozens injured in a bomb attack on a religious procession in Pakistan's Punjab province, officials say.
The attack targeted Shia worshippers in the town of Dera Ghazi Khan.
They were leaving a mosque when the bomb went off. It is not clear who carried out the attack or whether it was the work of a suicide bomber.
Sectarian tensions in southern Punjab have in recent years been aggravated by the growing strength of Sunni Taleban.
Police are investigating whether the attack was carried out by a suicide bomber.
"It appears to have been a suicide bombing, as there was no crater in the aftermath of the blast," local police chief Masud-ul-Hasan said.
Meanwhile, local police commissioner Hasan Iqbal told reporters: "It appears to have been a planted device."
He called it a terrorist attack aimed at Shias to create unrest.
Television footage showed bodies surrounded by debris and ambulances, with survivors wailing and beating their heads in grief.
Some reports speak of protests in the town.
Southern Punjab is home to a number of violent sectarian groups with links to al-Qaeda and the Taleban.
The BBC's Syed Shoaib Hasan in Islamabad says the banned Lashkar-e-Jhangvi, one of Pakistan's most ruthless militant groups, is blamed for most of the violence.
Lashkar-e-Jhangvi is a militant outshoot of the Sipah-e-Sahaba organisation which demands Pakistan be turned into a hard-line Sunni state.
The Lashkar has been blamed for a string of attacks.