A church was set ablaze and the group attempted to burn a Christian man alive in Sandha, Lahore after accusations the man had committed blasphemy.
Humayun Faisal was arrested at the time of the attack accused of burning pages of the Quran, but local people say he suffers from mental health problems.
Anti-persecution charity CLAAS told Premier the mob started attacking the town under the instruction of a local Muslim leader.
The organisation said police had told it that 22 people had been arrested in connection with the attack and that some of them had been found with weapons.
Nasir Saeed from CLAAS told Premier it appeared that authorities were taking the case seriously.
"This is a good sign that the police has started taking action against the perpetrators.
"It is a kind of lesson to other people not to take the law into their own hands."
He added: "The government has drafted a law to bring some changes.
"They want to stop vigilantly killing and they want to take action against people who take law into their own hands."
Premier's Antony Bushfield speaking to Nasir Saeed: