It was the second blast to hit a police vehicle and the fourth explosion in the past week. The incidents have been claimed by a previously unknown group calling itself "Taong Bayan at Kawal" (People and Soldiers), NCRPO chief Director Vidal Querol said.
He said the spate of attacks in Metro Manila was apparently meant to embarrass the Philippine National Police (PNP).
"Nakakahiya, ako bilang hepe ng Metro Manila ay nahihiya sa nangyayari (I am ashamed of myself being the police chief of Metro Manila and being apparently helpless against it)," Querol said.
"These criminals are taunting us, and doing a good job of it. But this does not contribute to the country’s progress, they are doing the opposite," he added.
The improvised explosive device created a three-inch deep crater near the police SWAT van’s right rear wheel, bending its fender.
Querol said the type of explosive could not immediately be determined and an investigation was underway.
He said security had been tightened inside the camp after the explosion and an investigation was being launched.
He would not confirm reports that the so-called Taong Bayan at Kawal was behind the bombing.
The group first surfaced last week after it claimed responsibility for the bombing of the Grepalife building in Makati City and weekend bombing attacks on police stations in Manila and Quezon City.
The group, however, denied any involvement in a pre-dawn market bombing in Lipa City that injured nine people on Sunday.
Last Sunday, a suspected homemade bomb exploded in a bus that was being used as a mobile police station and jail parked along the Elliptical Road in Quezon City, blowing a hole in the side of the vehicle but causing no injuries.
PNP chief Director General Arturo Lomibao ordered an immediate investigation of the attack.
Lomibao tasked Director Marcelo Ele Jr., chief of the PNP Directorate for Investigation and Detective Management (DIDM), to head the investigation of the spate of bombings.
The PNP chief also ordered strict security measures around Camp Crame against the possibility of another attack.
"We are just taking precautions. We don’t want any untoward incidents to happen at the camp," PNP spokesman Senior Superintendent Samuel Pagdilao Jr. explained.
Lomibao has directed all regional directors and camp commanders to implement stricter security measures.
The PNP chief reiterated his appeal to the public to keep calm and be vigilant.
Pagdilao said investigators were awaiting laboratory results to determine whether the same explosives were used in all four bombs.
Pagdilao added that investigators were still trying to establish whether the same group was responsible for all four explosions, including two earlier blasts — one that hit Grepalife building, which houses the office of Pacific Plans company that is facing a suit from its beneficiaries, and another at the house of Rodolfo "Bong" Pineda, an alleged illegal gambling operator in Pampanga.
Pagdilao noted that all the explosions occurred early in the morning, caused no injuries and appeared to be intended only to scare people.
He said it was too early to draw any conclusions. "We are taking the statement of the so-called Taong Bayan at Kawal claiming responsibility for the Quezon City and Manila incidents with prudent suspicion," he said in a statement.
"Some quarters may just be riding on these incidents to promote their own agenda. As far as we are concerned the (Kawal) group is non-existent," he said.
Malacañang warned that radical elements in the political opposition are planning to sow "terror" ahead of President Arroyo’s State of the Nation Address (SONA) in July in a fresh attempt to grab power.
While some groups claimed responsibility for the latest spate of bombings, presidential chief of staff Michael Defensor said they are more likely to be "the same people behind who wanted to bring down the President in the past but just changed their names."
"It is not the legitimate opposition who still participate in the democratic processes but the more radical and extremist opposition, the destabilizers… who we can see based on intelligence reports as really desperate to destabilize the government, who want to topple her, conduct bombings and assassinations," Defensor told reporters.
Defensor said the blasts could escalate leading up to Mrs. Arroyo’s SONA next month after her radical political opponents failed to stage another people power revolt and were unsuccessful in recruiting military and police personnel to their cause.
He noted the Oakwood mutiny was staged a day before she was to make her SONA in 2003 while calls for her to step down last year reached their peak also in July, when Senate President Franklin Drilon and former President Corazon Aquino asked her to resign.
The opposition has threatened to file another impeachment complaint against Mrs. Arroyo next month, shortly after Congress opens its third and final session.
National Security Adviser Norberto Gonzales maintained his allegation that opposition forces were involved in the incidents.
The opposition has been trying to force the President out of office since last June over allegations of corruption and electoral fraud.
Defensor added that Malacañang expects the group to continue its destabilization efforts that may include assassination plots against Mrs. Arroyo and Cabinet officials.
Defensor also dismissed speculation that the bombings were carried out upon orders of the Arroyo administration.
He said intelligence reports had revealed the group was bent on sowing terror.
Defensor called on the public to assist authorities in gathering information to stop future attacks.
On the other hand, former senator Vicente Sotto III accused the administration of trying to put the blame on the opposition in the absence of any other group taking full responsibility for the attacks.
"They are blaming the opposition because of lack of intelligence and someone to blame," Sotto said.
Makati City Mayor Jejomar Binay of the United Opposition (UNO), for his part, challenged Gonzales to name names.
"He has to clarify who among the opposition is involved in the bomb attacks since they said the opposition is not united," Binay said. — With Rhodina Villanueva, Paolo Romero, Michael Punongbayan, AP, AFP