Capping off a horrible, violent week with even more horrible violence, a bomb exploded in Lahore, Pakistan on Easter Sunday. According to authorities, a suicide bomber detonated an explosive in the parking lot of a popular park, killing at least 65 people and leaving around 300 more injured. Now, investigators are rushing to figure out who is responsible for the explosion in Pakistan.

A Taliban faction called Jamaat-ul-Ahrar has claimed responsibility for the attack, with a spokesman for the group telling Reuters,

The target were Christians. We want to send this message to Prime Minister Nawaz Sharif that we have entered Lahore. He can do what he wants but he won’t be able to stop us. Our suicide bombers will continue these attacks.

On Sunday evening, the site of the bombing, Gulshan-i-Iqbal Park, was more crowded than usual, with families out to celebrate the Easter holiday. Police noted that the blast occurred mere feet from the children's swings. Women and children were the overwhelming victims of the attack. Nasreen Bibi, a mother whose two-year-old child was injured, said that she and her family were there when the bomb was detonated, around 6:40 p.m. local time. “We were just here to have a nice evening and enjoy the weather," she said, according to The Guardian. "May God shower his wrath upon these attackers. What kind of people target little children in a park?”

In response to the bombing, the Punjab government ordered three days of mourning throughout the province, and closed all public parks.

In a statement on the official Malala Fund Twitter this week, 18-year-old Pakistani activist and Nobel laureate Malala Yousafzai, added her own condolences, stating solemnly

I am devastated by the senseless killing of innocent people today in Lahore. My heart goes out to the victims and their families and friends. I condemn this attack in the strongest possible terms. We stand together with the families of the victims. Pakistan and the world must unite. Every life is previous and must be respected and protected.
ARIF ALI/AFP/Getty Images
Pakistani rescuers use a stretcher to shift a body from a bomb blast site in Lahore on March 27, 2016. At least 25 people were killed and dozens injured when an explosion ripped through the parking lot of a crowded park where many minority Christians had gone to celebrate Easter Sunday in the Pakistani city Lahore, officials said. / AFP / ARIF ALI (Photo credit should read ARIF ALI/AFP/Getty Images)

Punjab, of which Lahore is the capital city, is the biggest and wealthiest province in Pakistan, a country wracked by sectarian violence and Taliban fighting. Punjab has generally been more peaceful than other parts of the country, but it has weathered attacks before. In March 2015, two Christian churches in Lahore were targeted by suicide bombers, with Pakistani Christians accusing the government of failing to protect them.

In a statement about the attacks, White House National Security Council spokesman Ned Price said, “The United States stands with the people and government of Pakistan at this difficult hour. We will continue to work with our partners in Pakistan and across the region … to root out the scourge of terrorism.”

Officials warn that the death toll may continue to rise, due to the many injuries sustained.