Police Have Arrested A Number Of People Linked To Pakistan's Suicide Bombs. Investigate How The Perpetrators Are Strictly Security

The explosion of a mosque in Peshawar, Pakistan. (Twitter/@HajjatiSmart)

JAKARTA - Pakistani police have arrested a number of people in connection with a suicide bomb explosion at a mosque that killed more than 100 people, investigating how the perpetrator entered the mosque, including the possibility of internal assistance to avoid security checks.

The bombing that destroyed the upper floor of the mosque in Peshawar, which is close to the Afghan border, was the deadliest in a decade since the twin suicide bombings at the All Saints Church killed dozens of congregants in September 2013.

Monday's explosion occurred as hundreds of worshipers gathered for the Zuhur Prayer at a mosque built specifically for police, as well as for their families living in heavily fortified areas.

Of the victims who died in the suicide bombing at the mosque, three were not police, the rest were police officers.

"We have found some very good clues, and based on these clues we have made several major arrests," Peshawar Police Chief Ijaz Khan told Reuters.

"We can't rule out internal help, but because the investigation is still in progress, I can't share more details," he said.

Investigators, who include counter-terrorism and intelligence officials, are focusing on how the attackers managed to break into military and police checkpoints leading to the Police Line District, a colonial-era self-residential settlement in the city center that is home to the middle class, as well as lower-ranking police personnel and their families.

Defense Minister Khawaja Asif said the bomber was in the first row in the prayer room when he attacked. The attack's body has been found, Moazzam provincial police chief Jah Ansari told Reuters.

"We believe the attackers are not organized groups," he added.

The most active militant group in the region, the Pakistani Taliban or Tereek-e-Taliban Pakistan (TTP), has denied responsibility for the attack, which so far has not been claimed by any group.

Meanwhile, Interior Minister Rana Sanaullah told parliament the breakaway factions from TTP were to blame.

It is known, TTP is an umbrella group for Sunni factions and sectarians against the government in Islamabad. The group recently stepped up attacks on police.