Story highlights

NEW: President Zardari expresses condolences, Pakistan's official news agency says

Preliminary investigations say the blast was caused by a bomb, police say

At least 14 people are killed, police say

Islamabad, Pakistan CNN  — 

At least 14 people were killed and 20 injured in a bomb blast in the Pakistani town of Khan Pur, a police official said Sunday.

Preliminary investigations show the explosion was caused by a bomb planted along a Shiite Muslim procession route, police official Sohail Chatta said.

Police are still waiting for the results of the bomb squad investigation, he said, adding that no one has claimed responsibility for the attack.

President Asif Ali Zardari expressed grief and sorrow over the loss of lives in the incident, the country’s official APP news agency reported.

Khan Pur is in central Pakistan, in the district of Rahim Yar Khan in Southern Punjab Province.

The dead were Shiite Muslims marking the holy day of Chehlum, the 40th day after the anniversary of the death of Imam Hussain, the grandson of the prophet Mohammed.

Pakistan has a long history of sectarian violence.

Shiite processions on religious holidays are regularly targeted by Sunni militants.

CNN’s Reza Sayah contributed to this report.