Muslims pray to celebrate the Eid al-Adha holiday at a mosque in Islamabad, Pakistan, on Sept. 13, 2016. (B.K. Bangash/AP)

A suicide bomber touched off a deadly blast Friday inside a crowded mosque in Pakistan’s tribal area near the Afghan border, killing at least 24 people marking the end of a Muslim festival, a government official said.

Naveed Akbar, the assistant administrator in the area of the attack, predicted that the death toll could rise. More than two dozen people were reported wounded, many seriously, he said.

There was no immediate claim of responsibility, but the tribal areas are strongholds of various militant groups that include one faction blamed for recent assaults in the vicinity.

The attack came a day after a woman was killed in the same area, Mohmand district, when militants threw grenades at and opened fire on the house of a pro-government tribal elder, officials said.

The suicide bomber entered a village mosque as more than 300 worshipers were attending weekly prayers just after noon. Shouting “God is great,” he detonated the explosive, an official said.

The attack came just after the final day of Eid al-Adha, a Muslim festival that includes animal sacrifices and several days of celebration. The Friday prayers were a final ritual after a busy week of feasting and family gatherings. 

Akbar, the assistant administrator, said that the suicide bomber “and his facilitators” appeared to have timed the attack to create a “high casualty ratio,” since Friday prayers are the most heavily attended of the week.

Officials said they suspected that Jamaat-ul-Ahrar, a splinter group of the Pakistani Taliban, was responsible for the attack. The group had claimed it carried out the killing of a Mohmand tribal elder last week.

The same group also claimed responsibility for a recent suicide bombing that killed 14 people outside a courthouse in nearby Mardan and also for a massive bombing outside a hospital in the southern city of Quetta in August, which killed more than 70 people, most of them lawyers.

Pakistan’s army launched a massive operation two years ago against the Taliban and other armed militant groups in the country’s border tribal areas. Many of those groups’ fighters were driven into Afghanistan and took up arms against the Kabul government, some in alliance with Islamic State militants.

Constable reported from Islamabad, Pakistan.