It was the biggest of this kind of attacks in 2010 when two separate unknown groups attacked two worship places of a minority group, Ahmadis on Friday in Pakistan's eastern city of Lahore.

The two attacks were carried out nearly simultaneously, at Garhi Shahu and Lahore Model Town, 15 km apart. Police said at least 73 people were killed and 100 others were injured. Several attackers were killed and one was captured. During the shootout a policeman was killed and four others, including senior police officials, were injured.

The time of the terrorizing act was very important to note. The attack was made on Friday when more than 2,000 of Ahmadis, also known as Qadiyani, gathered in the worship places. On the same day, Pakistan was also celebrating the Youm-i-Takbeer (or Pakistan's Self Reliance Day), when Pakistan became a nuclear power on May 28, 1998.

Two separate groups identified themselves as Tehrek-e-Taliban Pakistan Punjab wing and Al-Qaeda Al-Jihad Punjab wing claimed responsibility for the incident. The two names were new for observers.

Therefore, several questions were raised about the real culprits behind the attacks against Ahmadis, a non-Muslim minority group in Pakistan.

Some people believed that some foreign hands were involved in the incidents as May 28 was an important day for Pakistan. Some officials like commissioner of Lahore, the capital of the eastern province Punjab, doubted some foreign forces for carrying out the attacks when they answered local media's questions.

However, analysts did not agree that foreign hand could be involved in this particular incident. Retired Lieutenant General Talaat Masood, a seasoned defense analyst, said that Pakistan has a long history of sectarian violence and Qadaynis were opposed in history.

"The militants groups in Pakistan act in accordance with their ideological orientation and training and there are certain groups that consider killing of infidels or non-believers as good, and all those who are not in line with their believes are considered as infidels," he added.

Masood dubbed the incident as a sectarian violence and ruled out involvement of any foreign hand. He doubted involvement of even Tehrek-e-Taliban Pakistan (TTP).

Rahimullah Yousafzai, an expert on militancy and well-known analyst, told Xinhua that the militants want to convey the message that they are targeting non-believers besides America. He also ruled out foreign involvement in the attacks against Ahmadis.

If TTP and foreign hands are not behind the attack, then who planned it?

Yousafzai and Masood agreed that the Punjab based militants, sometimes referred as Punjabi Taliban, are responsible for the action. Masood said that Pakistan is facing the problems like Friday's incident, as in the past no action was taken against the groups promoting violence inside the country.

Meanwhile, investigation is going on and Punjab chief minister have ordered authorities to present report till late night. Punjab Law Minister said that the arrested attacker, believed to be aged between 15 and 18, was a student of Karachi-based religious seminary.