MANILA, Philippines – Two explosions took place Monday morning in Metro Manila, causing no injuries and leaving only minimal damage as the police called on the public not to panic.

The first blast occurred at the headquarters of San Miguel Corp. (SMC) at the corner of San Miguel Drive and Doña Julia Vargas Avenue in Ortigas Center, Mandaluyong City, at around 3:02 a.m.

"There was only partial damage. Some of the letters [on a sign bearing the company's name] fell off due to the strength of the explosion but the logo was not affected," Chief Superintendent Benjardi Mantele, director of the Eastern Police District (EPD), said.

According to Senior Superintendent Carlos de Sagun, Mandaluyong police chief, the explosive was apparently placed in a dark canvas bag, torn pieces of which were recovered at the scene.

"We still don't know if it was TNT or C4. We'll know that from the results of the investigation conducted by Scene of the Crime Operatives who examined the site," he said.

Mantele added that he had asked the SMC security officer to station guards near the area where the explosion occurred. He also ordered increased police visibility in the area especially "from sunset to sunrise."

"There were no witnesses. When the guards came rushing to the scene, the one who left the explosive was already gone," he said.

Although the motive was still under investigation, De Sagun said the explosion was likely targeted at SMC and not meant to terrorize the Ortigas business district as a whole.

Almost two hours after the first blast, an improvised explosive device also went off, this time in front of the Puregold Supermarket on Commonwealth Avenue in Quezon City.

The impact damaged the awning in front of the main entrance and left a small crater on a ramp leading to the establishment, said Inspector Arnulfo Franco of the Quezon City Police District (QCPD) Explosive and Ordnance Division.

"But we still have to determine if the two incidents are related because the technical aspect of the investigations are not yet finished," Franco said.

Security guard Joel Galmorin told the police that before the blast, he saw a man in a taxi cab throw a white plastic bag on the supermarket ramp.

The bag was emitting white smoke just seconds before it exploded, he added.

"The suspects could have lighted the explosive before lobbing it. The fact that there's white smoke before the explosion means there is a time fuse in the improvised explosive," Franco said.

On Oct. 30, two explosions took place in Quezon City and in the Pasig side of the Ortigas business district. As in yesterday's bombing incidents, there were no injuries while damage to property was minimal.

Franco noted that both explosions in Quezon City were similar because they "involved a device which first emitted smoke before exploding. Both of them had time fuses."

He added that his men were still sifting through the recovered debris and at press time, had yet to identify the components of the explosive used in yesterday's incident.

QCPD director Chief Superintendent Elmo San Diego said they were still trying to establish a motive for the blast at the supermarket.

"Initially, we are looking at an attempt to harass perhaps the supermarket's owner. We don't think it's a terrorist act," he said, adding that the explosion was not meant to kill or cause serious damage because there was no shrapnel recovered at the blast site.

"We will also compare notes with the EPD on the technical aspect of the report to see if there are signatures or identifying marks on the device which would mean that only one person made them," he said.

Meanwhile, Philippine National Police chief Jesus Verzosa asked the public to stay calm following the twin explosions.

He said there was no reason to believe that the bombings were the handiwork of groups out to sow terror in the metropolis.

Director Roberto Rosales, National Capital Region Police chief, told the Philippine Daily Inquirer they were still investigating the link between the twin blasts.

"To prevent such incidents, I have directed district directors, even before, to intensify police visibility in choke points," he said, adding that gas stations, oil depots and public transport systems should be well protected. With Erika Sauler and Marlon Ramos