ISLAMABAD -- A bomb killed 12 women and children at a gathering of thousands of Shia Muslims in the grounds of a Mosque in central Pakistan, hospital officials said on Friday.

It was not immediately clear who planted the bomb, which wounded at least 23 people when it went off late on Thursday in Bhakkar in Punjab Province, but residents said sectarian violence between militants from the Shia and Sunni sects of Islam was most likely to blame.

"It is religious terrorism. You know what is going on in Pakistan," local Shia leader Wizarat Naqvi told Reuters, adding three of the bodies were beyond recognition and funeral preparations were underway.

A witness said those killed included nine women and three children.

"We have now 14 wounded people. The rest have been discharged after administering first aid," a hospital official told Reuters by telephone. "All of the wounded people are out of danger."

The explosion occurred at around 11.30 P.M. (1730 GMT) in the women's section of a huge segregated gathering of Shia in grounds belonging to a Shia mosque and cemetery.

"It appeared to be a time device buried in the earth. It created a two to three feet crater (one meter) in the ground," Naqvi said.

Residents said thousands of Shias were at the mosque for an annual gathering to mourn the death of the Prophet Mohammad's grandson Hussain, who died with 72 followers and family members at Karbala in Iraq in 680 Ad during a battle with rival Yazid.

"Some unknown persons planted the explosive device," the official APP news agency quoted Bhakkar district police chief Khuram Gulzar as saying.

Until late into the night, mosques throughout the city were making announcements to help trace children lost in the chaos that followed the blast, the English-language daily the ***NEWS *** reported.

Violence between militants from the Sunni and Shia sects of Islam has killed hundreds of people in Pakistan during the last decade. Shias make up about 15 percent of Pakistan's 140 million people.