A bomb exploded in the women's section of a Shiite Mosque in a Pakistani province wracked by religious violence, killing 12 female worshippers and wounding at least 13 other people, hospital officials said Friday. 

It's not known who planted the powerful bomb that went off around midnight Thursday in Bukker in eastern Punjab province, about 300 miles southwest of the federal capital of Islamabad. 

"The bomb was planted on the women's side and all the dead were women," said Mohammed Nisar, a doctor at the only hospital in Bukker where the dead and wounded were taken. 

Mosques are segregated. 

A senior leader of the outlawed Shiite group Tehrik-e-Jafria, Ali Raza Gardezi, said the attack on women and children was an act of terrorism aimed at creating unrest and sectarian disharmony. 

Gardezi said only the enemy of Islam could be behind the bomb attack on the Muslims as "no Muslim can do it," Gardezi said. 

Faiz Mohammed Awan, medical superintendent of the hospital at Bukker, confirmed that they have received 12 bodies at the hospital while 13 wounded are being treated. 

Police have not made any arrests, but Pakistan, and eastern Punjab province in particular, has been wracked by religiously motivated violence in recent years. Attacks by rival radical elements of the Sunni and Shiite sects of Islam have killed hundreds. 

The usual culprits involved in the killing of Shiite Muslims have been members of the violent Sipah-e-Sahaba Pakistan or Guardians of the Friends of the Prophet group, banned by Pakistan's military president Gen. Pervez Musharraf. The organization reviles Shiite Muslims as outside the pale of Islam. 

Since January dozens of Shiite Muslims have been killed in Pakistan. Many of the deaths have been target killings and have occurred both in the Punjab province and in the country's southern Sindh province, of which Karachi is the capital. 

During the last week in Karachi a Shiite Muslim doctor was shot and killed as well as the Shiite Muslim owner of a pharmacy. No arrests have been made in the two drive-by shootings. It's not known if the killings were carried out by the same people or organization. 

No one has claimed responsibility for any of the killings. 

Previously Hasan Turabi, the head of the Tehrik-e-Jafria, blamed the upsurge in killings of Shiite Muslims on the return to Pakistan of militant Sunni Muslims from neighboring Afghanistan following the collapse of the Taliban. 

Turabi said the Taliban, a movement dominated by Sunni Muslims, espoused the same philosophy as Pakistan's radical Sunnis, and harbored those who had killed Shiites in Pakistan. With the fall of the Taliban these radical elements returned home, he said. 

Police said they were investigating the explosion in Bukker.