The attack took place in Jaranwala in the industrial district of Faisalabad, said police spokesperson Naveed Ahmad. The two Christians were accused of blasphemy, he said, adding they and family members had fled their homes.

Resident Shakil Masih said he heard announcements inciting the mob and then saw crowds heading towards his Christian area.

“I left my home immediately with my family. Several other families did the same,” he told Reuters.

Over 100 people were arrested, Punjab’s caretaker information minister, Amir Mir, said later on Wednesday. “People who attacked the churches are being identified through video footage,” he said.

Police said the case against the Christians relates to pages of the Koran found with some derogatory remarks written in red.

Blasphemy is punishable by death in Pakistan and though no one has ever been executed for it, numerous accused people have been lynched by outraged crowds. A former provincial governor and a minister for minorities have also been shot dead because of blasphemy accusations.

Rights groups say accusations of blasphemy are sometimes used to settle scores. Hundreds of people are languishing in prison after being accused because judges often put off trials, fearing retribution if they are seen as being too lenient, they say.

“The frequency and scale of such attacks — which are systematic, violent and often uncontainable — appear to have increased in the last several years,” said the Human Rights Commission of Pakistan.

The rights group called for the setting up and equipping of special police forces to protect religious minorities’ sites of worship, as directed by a 2014 Supreme Court judgment.

Caretaker Prime Minister Anwar ul Haq Kakar called for stern action against those responsible for Wednesday’s violence. “I am gutted by the visuals coming out,” he said.

The United States was “deeply concerned that churches and homes were targeted,” said State Department Deputy Spokesperson Vedant Patel.

“We urge Pakistani authorities to conduct a full investigation into these allegations and call for calm for all those involved,” Patel told reporters.

A Christian leader, Akmal Bhatti, said the crowd had “torched” at least five churches and looted valuables from houses that had been abandoned by their owners. Hundreds of people also blocked a nearby highway.

Video showed men attacking a church with sledgehammers and setting fires.

The mob was made up of thousands of people led by local clerics, mainly from an Islamist political party called Tehreek-e-Labaik Pakistan (TLP), a government source said.

The TLP denied inciting the violence and said it had worked with police to try to calm things down.

(Additional reporting by Humeyra Pamuk and Simon Lewis in Washington; Editing by Alexandra Hudson and Rosalba O’Brien.)