(AP) -- The death toll from a massive suicide bombing targeting Christians gathered on Easter in the eastern Pakistani city of Lahore rose to 70 on Monday, underscoring the ability of the militants to stage large-scale attacks despite a months-long military offensive targeting their hideouts.

Meanwhile, in the capital of Islamabad, extremists protested for a second day outside Pakistan's Parliament and other key buildings in the city center. The demonstrators set cars on fire, demanding that the authorities impose Islamic law or Sharia. The army, which was deployed Sunday to contain the rioters, remained out on the streets around the Parliament and key buildings on Monday.

The Lahore bombing, which was claimed by a breakaway Taliban faction that has publicly supported the Islamic State group, took place in a park that was crowded with families, with many women and children among the victims. At least 300 people were wounded in the bombing.

Also Monday, Pakistan started observing a three-day mourning period that was declared after the Lahore attack.

Even though a breakaway Taliban group, known as Jamaat-ul-Ahrar, said it specifically targeted Pakistan's Christian community, most of those killed in Lahore were Muslims, who were also gathered in the park for the Sunday weekend holiday. The park is a popular spot in the heart of Lahore.

Of the dead, 14 have been identified as Christians, according to Lahore Police Superintendent Mohammed Iqbal. Another 12 bodies have not yet been identified, he said.

The attack underscored both the precarious position of Pakistan's minorities and the fact that the militants are still capable of staging wide-scale assaults despite a months-long military offensive targeting their hideouts and safe havens in remote tribal areas.

Ahsanullah Ahsan, a spokesman for the breakaway Taliban faction, told The Associated Press late Sunday that along with deliberately targeting Christians celebrating Easter, the attack also meant to protest Pakistan's military operation in the tribal regions. The same militant group also took responsibility for the twin bombings of a Christian Church in Lahore last year.

In Turkey, President Recep Tayyip Erdogan condemned the Lahore bombing, saying that in targeting a park filled with children, the attack "revealed the face of terror, which knows no limits and values."

France expressed its "solidarity in these difficult moments" to the authorities and the people of Pakistan and underlined "the inflexible will of our country to continue to battle terrorism everywhere."

In Islamabad, extremists had marched into the city on Sunday in protest of the hanging of policeman Mumtaz Qadri in February. Qadri was convicted for the 2011 murder of governor Salman Taseer, who was defending a Christian woman jailed on blasphemy charges. Taseer had also criticized Pakistan's harsh blasphemy laws and campaigned against them.

As the protesters reached an avenue leading to the Parliament, the march turned violent, with Qadri's supporters smashing windows and damaging bus stations. Police fired tear gas but could not subdue the crowds, which remained in the capital.

On Monday, they rallied anew, demanding that the Christian woman also be hanged and that authorities impose Islamic law or Sharia. The woman, Aasia Bibi, is still in jail facing blasphemy charges.

The army deployed Pakistan paramilitary Rangers as well as about 800 additional soldiers from neighboring Rawalpindi to Islamabad, to protect the center, which houses main government buildings and diplomatic missions.

In recent weeks, Pakistan's Islamist parties have been threatening widespread demonstration to protest what they say is Prime Minister Nawaz Sharif's pro-Western stance. They have also denounced provincial draft legislation in Punjab outlawing violence against women.

Sharif had also this month recognized holidays celebrated by the country's minority religions, the Hindu festival of Holi and the Christian holiday of Easter.

In Lahore, dozens of families were bidding final farewell to their slain kin on Monday.

Shama Pervez, widowed mother of 11-year-old Sahil Pervez who died in the blast, was inconsolable during funeral prayers. Her son, a fifth grader at a local Catholic school, had pleaded with her to go to the park rather than stay home on Sunday, and she said she finally gave in.

Forensic experts sifted through the debris in the park on Monday. The suicide bomb had been a crude devise loaded with ball bearings, designed to rip through the bodies of its victims to cause maximum damage, said counter-terrorism official Rana Tufail. He identified the suicide bomber as Mohammed Yusuf, saying he was known as a militant recruiter.

Analyst and prominent author of books on militants in Pakistan, Zahid Hussain, said Sunday's violence was a coordinated show of strength by the country's religious extremists, angered over what they see as efforts to undermine their influence.

The military launched an all-out offensive against militants in the North Waziristan tribal region bordering Afghanistan in June 2014. The operation, called Zarb-e-Azb, has seen over 3,000 militants killed, according to the army. In December 2014 , the Taliban retaliated with one of the worst terror assaults in Pakistan, attacking a school in northwestern city of Peshawar and killing 150 people, mainly children.

Hussain said the government has been sending mixed signals to Islamic extremists -- on the one hand allowing banned radical groups to operate unhindered under new names and radical leaders to openly give inciting speeches, while on the other hanging convicts like Qadri and promising to tackle honor killings and attacks against women.

"It is one step forward and two steps backward," says Hussain. "The political leadership has to assert itself and say 'no' to extremism once and for all."

Army chief Gen. Raheel Sharif promised Pakistan "will never allow these savage non-humans to over run our life and liberty."

Prime Minister Sharif, meanwhile, cancelled a planned trip to Great Britain on Monday and held a high-level security meeting.

In Pakistan's largest city, Karachi, the Press Club was ransacked by pro-Qadri supporters on Sunday. Several Pakistani journalists were roughed up and some equipment was damaged.

On Monday, extremists were regrouping in Karachi ahead of rallies in the country's financial center.

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Gannon reported from Islamabad. Associated Press Writers Asif Shahzad and Munir Ahmed in Islamabad and Asim Tanveer in Multan, Pakistan, also contributed to this report.