The police also registered two FIRs - one against Taliban militants and the other against those responsible for burning alive two "suspects" who were detained after the blasts.
The security of churches across Pakistan has been stepped up on the direction of Prime Minister Nawaz Sharif.
"Police have taken some 17 suspects into custody during a search operation launched last evening," Lahore police spokesman Niyab Haider told PTI.
"We have also registered two murder cases against the Taliban militants and those involved in lynching of two men," Haider said, adding that an investigation team had also preserved the forensic evidence at the blasts site.
Tahreek-i-Taliban Pakistan splinter group Jamat-ul-Ahrar has claimed the responsibility for the attacks on Roman Catholic Church and Christ Church in Christian-dominated Youhanabad area during Sunday mass.
The same group had claimed the responsibility of a suicide attack at Wagah border in September last year in which 60 people were killed.
Inspector General Police Punjab Mushtaq Ahmed Sukhera told reporters that there had been a similarity in Wagah Border and Youhanabad churches blasts.
"There has been a clear similarity between the Wagah and Youhanabad suicide attacks," he said.
When the guards stopped them from entering the churches they blew themselves up at the gates.
After the blasts, police detained two suspects from the site and shifted them to a vehicle when a group of charged youngsters got hold of them.
The enraged mob started thrashing the two suspects. After beating them severely, the mob set them on fire. Their charred remains were later found at the site.