In an interview on Unang Hirit, Metro Manila police chief Director Nicanor Bartolome said their initial findings showed the explosive device in Tuesday's bus blast used an 81-millimeter mortar and a cell phone as a detonator.
"Kaninang madaling-araw, nabuo na ang mga fragment. Na-reconstruct natin at lumalabas na 81-mm mortar shell and ginamit at cell phone ang ginawang triggering device," Bartolome said.
But Bartolome refused to say for now what group authorities suspect to be behind the blast.
In a separate interview on dwIZ radio Bartolome said, "We are digging deeper into who the culprit is. An 81-mm mortar can be found in the military's arsenal but such an explosive has already been used in past bombing attacks in Mindanao."
For his part, Interior Secretary Jesse Robredo said the initial findings indicate the bomb was similar to those used by groups in Central Mindanao.
Robredo, in a separate interview on dzBB radio, cited past incidents that used a similar IED, including the Rizal Day Bombing on Dec. 30, 2000; and the Valentine's Day bombing of a bus in Makati City in 2005.
"Ang gamit nito base sa karanasan nagamit ito sa Central Mindanao (Based on our experiences, this has also been used extensively in Central Mindanao," he said, referring to the buses extortionist groups there had bombed.
Meanwhile, Robredo gave his personal cell phone number for the public to send in tips to authorities.
He said he will personally answer the number 0918-8883454, which he said will be switched on 24 hours a day.
"I-text ninyo para makuha agad. Ginagarantiya namin pangangalagaan namin ang seguridad at confidentiality (Just send your tips via text. I guarantee you we will protect your identity)," he said.
Meanwhile, the death toll from the bus blast rose to five early Wednesday, after one of the victims succumbed to her wounds at 1:55 a.m. while being treated at the Makati Medical Center.
As of this posting, four victims were being treated at the Ospital ng Makati, while nine were at the St. Luke's Medical Center-Global City in Taguig City. — LBG, GMANews.TV