PESHAWAR, Pakistan/ISLAMABAD (Reuters) – The Taliban faction that killed at least 70 people, many of them children, in a park in Lahore on Easter Sunday has been quickly gaining attention in militant circles.

Jamaat-ur-Ahrar’s recent rise to prominence – Sunday’s attack was the fifth it has claimed since December – plus its onetime pledge of allegiance to Islamic State show the fractured and sometimes competitive nature of Pakistan’s myriad militants.

“They are nowadays the main group claiming attacks in the past few months,” said Mansour Khan Mehsud, lead researcher of the FATA Research Group, said of Jamaat-ur-Ahrar.

In Sunday’s attack, 29 of the 70 killed were children enjoying an Easter weekend outing. Pakistan is a majority Muslim state but has some two million Christians, and Easter is a public holiday.

It was the most deadly attack in Pakistan since the December 2014 massacre by the Taliban of 134 school children at a military run academy in the northwestern city of Peshawar.

A spokesman for Jamaat-ur-Ahrar (JA) on Monday threatened other attacks, including more against religious minorities.

“We don’t target women and children, but Islam allows us to kill men of the Christian community who are against our religion,” spokesman Ehansullah Ehsan said.

The group’s leader, Omar Khalid Khorasani, has a background that reads like a history of Pakistani militancy.

Born Abdul Wali in a small village called Lakaro in the northwestern Mohmand tribal region, Khorasani started out as an anti-India jihadist fighting in Kashmir, according to a long-time friend and militant colleague who spoke on condition of anonymity.

He later joined the Pakistani Taliban in 2007 to fight the government to establish strict sharia Islamic law.

In 2013, Khorasani was one of the candidates to lead the Pakistani Taliban – who are separate from but loosely allied with the Afghan Taliban – after its chief Hakimullah Mehsud was killed in a U.S. drone strike.

After losing out to Maulana Fazlullah, Khorasani left the next year to form his own group.

Jamaat-ur-Ahrar in September 2014 swore allegiance to Islamic State, also known as Daesh.

“We respect them. If they ask us for help, we will look into it and decide,” spokesman Ehsan told Reuters of Islamic State, while rejecting the main Pakistani Taliban leadership.

By March 2015, however, the group was again swearing loyalty to the main Pakistani Taliban umbrella leadership. The reason for its return to the fold remains murky, but JA never specifically disavowed Islamic State either.

Khorasani was seriously wounded in a NATO air strike in eastern Afghanistan last year, Ehsan confirmed, but said he has fully recovered and is in hiding. Like many Pakistani militants, Jamaat-ur-Ahrar’s fighters sometimes flee into Afghanistan to escape a Pakistani army crackdown along the border that began in 2014.

Pakistani authorities have expressed fears that the ideology of the Middle East-based Islamic State – which places greater emphasis on killing Christians and minority Shia Muslims – could intensify sectarian violence in Pakistan.

Targeting minorities is not-uncommon among Pakistan’s predominantly Sunni Muslim militants, but it is a far more pronounced trait of Islamic State.

Jamaat-ur-Ahrar had previously targeted Christians – in March 2015, it claimed two church bombings in Lahore that killed 14 people – but researcher Mehsud said he doubted JA’s loose affiliation to Islamic State was the cause.

Pakistan has been plagued by militant violence for the last 15 years, since it joined a U.S.-led campaign against Islamist militancy after the Sept. 11, 2001, al Qaeda attacks on the United States.

While the army, police, government and Western interests have been the prime targets of the Pakistani Taliban and their allies, Christians and other religious minorities have also been attacked by various factions.

Nearly 80 people were killed in a suicide bomb attack on a church in the northwestern city of Peshawar in 2013.

JA is vying for attention in the militant-saturated northwest that has some 60-70 armed Islamist groups, researcher Mehsud said.

“They target Christians and other minorities because it will get media attention … this is not something new,” he said. “They want to strike fear and show that they are still here and the military has not defeated the Taliban.”

(Additional reporting by Asad Hashim and Mubasher Bukhari; Writing by Kay Johnson; Editing by Ruth Pitchford)