Lahore, Pakistan (CNN) -- A dozen men who police said had been arrested over the bombing of a shrine in Pakistan were not involved in the attack, Lahore Police Chief Aslam Tareen told CNN Monday.
Suicide bomb attacks killed 50 people and injured more than 200 at a Lahore shrine on July 1.
Pakistani authorities said earlier they arrested 12 people in connection with the attack and recovered ammunition and weapons during the arrests in two neighborhoods in Lahore.
But Monday Tareen said the original reason given for their arrests was incorrect.
Officials planned to hold an emergency security meeting Monday to discuss ways to counter militant attacks. Pakistani Prime Minister Syed Yusuf Raza Gilani called for the meeting Saturday, saying the country cannot afford the "brunt of terrorism."
As public outrage grows, police and politicians are under growing pressure to show results after the deadly blasts that occurred when a pair of suicide bombers detonated their explosive vests outside the Data Darbar, a famous Sufi shrine complex.
One of the bombs detonated in the shrine's courtyard, while the other exploded on the shrine's lower level, police said.
On Friday, angry Pakistanis -- some wielding guns for revenge -- took to the streets of Lahore in protest. Many are troubled by the spread of bloodshed from the Afghan border areas to the heartland.
They are also concerned about attacks on Islamic holy sites.
Pakistan's Punjab province, of which Lahore is the capital, has been the scene of carnage in recent weeks, including a bloody attack on a hospital and another targeting Ahmadis.
Sunni and Shiites do not consider the Ahmadis as a part of Islam because they do not regard Mohammed as the last prophet sent by God. As such, they have been targeted by Islamic extremists.
But Thursday's attack was at a revered Sufi shrine. Sufism is an ancient, mystical form of Islam that is generally more tolerant.
The Human Rights Commission of Pakistan expressed alarm over the attacks and called on both the government and Muslim clerics to stand up to extremism.