"Some of the detained suspects belong to banned religious groups," said Senior Superintendent of Police Zulifqar Hameed.
A large Shia procession was on its way to the Karbala Gamay Shah `imambargah` or prayer hall yesterday when the suicide attacker blew himself up after being challenged by policemen in the Lohari Gate area of the old quarters of Lahore.
"Had the teenage bomber managed to reach the procession, the devastation would have been greater," Hameed said.
The bomber, believed to be 14 or 15 years old, was wearing a suicide jacket and carrying a bag filled with explosives.
"There were explosives in the bag and the boy probably wanted to install it somewhere along the route of the procession besides blowing himself up," Hameed said.
Shortly after the attack in Lahore, a suicide bomber struck policemen guarding another Shia procession in Karachi.
Three persons were killed in that attack.
Last year, two bomb blasts in the Lohari Gate area of Lahore had caused death and destruction on a large scale.
On July 1 last, over 40 people were killed and scores injured when two suicide bombers struck the Data Darbar shrine. Two months later, two suicide attacks targeting a Shia procession killed 40 people.
The Tehrik-e-Taliban Pakistan has claimed responsibility for most of these attacks, including yesterday`s strike in Lahore.
Punjab police chief Javed Iqbal today said an investigation team has been formed to look into the Lohari Gate suicide attack.
He was speaking to reporters at the funeral prayers for policemen killed in the attack.
The funeral prayers were attended by Governor Latif Khosa, Chief Minister Shahbaz Sharif and a large number of policemen.
The Chief Minister paid tribute to the dead policemen and promised to look after their families.
Sharif was embroiled in a controversy last year when he asked the Taliban to spare Punjab province, saying his PML-N party and the militants were against the policies of former President Pervez Musharraf.