Suspects responsible for the explosion at the Mt. Carmel Cathedral in Jolo were seen on the CCTV camera footage.

Interior Secretary Eduardo Ano in a press briefing in Jolo Monday said they saw the alleged suspects enter the church before the explosion.

Though authorities are pointing to the "Ajang-Ajang" group of the Abu Sayyaf terrorist group operating in the urban area like Jolo, Ano said they are still waiting for their investigation to finished to see if the suspects in the CCTV are really from that group.

Philippine National Police (PNP) Director General Oscar Albayalde said they still don't have evidence that the perpetrator is a suicide bomber.

"We still don't have evidence that it's suicide bombing," Albayalde said in the same briefing.

According to the PNP bomb experts, the improvised bomb was big since the shrapnel was spread a few meters away from the scene of the blast

"Although according to SILG earlier, it is very unlikely to enter the place without being noticed if you are wearing a bag and if you will also leave a big bag," he said.

Albayalde said the suspects used GI sheet in creating the bomb.

"It's probably as thick as a container of canister of milk that weighs around two kilos... that is our assumption. There were no shrapnel used. That (GI sheet) became the shrapnel," he said.

"The substance used until now is not certain," he added.

He said this kind of act could not be done by only one person.

Asked if there are lapses in the security, Albayalde said the twin blasts that resulted to at least 20 people dead and 112 wounded will serve as a lesson.

He said the reason that the perpetrators passed through security forces is because there has not incident like this for the past years, where suspects left an explosive device inside the church.

"According to the priest, there are incidents of grenade throwing outside, not inside," he added.

Albayalde said the church were able to experienced 10 to 11 incidents of grenade throwing and also assassinations.

"This is the worst incident happened that why we will be (checking) possible lapses from our security forces on the ground both from the Armed Forces of the Philippines and the Philippine National Police," he said. Ella Dionisio/DMS