BANGKOK — A blast blew out the side of a residential building in a Bangkok suburb Tuesday killing three people and injuring nine, emergency workers said, as police speculated the explosion could have been caused by a bomb.
Police had yet to establish the cause of the blast, which took place around 6 p.m., and there was no obvious reason that the 5-story apartment block in Nonthaburi province just north of the Thai capital might be a target.
TNN cable news channel reported that police explosives experts were speculating that the blast was caused by TNT or C4 explosive, perhaps used in a bomb as big as 50 kilograms (110 pounds).
Dozens of bombings have plagued Bangkok this year, both during anti-government protests from March to May and in the months since the military cleared the streets, but none of such magnitude. Small blasts since July have killed one person and wounded a dozen.
There have been no claims of responsibility for any of the attacks.
Col. Sansern Kaewkamnerd, spokesman for the special army-led body in charge of security since a state of emergency was declared during the political unrest, said he did not have many details, but conceded the blast could be linked to politics.
He said the special agency, the Center for Resolution of the Emergency Situation, was evaluating the incident.
"We cannot be certain that it is political. ... We have to look at all factors and motivations," Sansern told The Associated Press.
TNN said police explosives experts believed Tuesday's blast could have been caused by bombs similar to those used by Islamic separatist insurgents in southern Thailand, who have been waging a terror campaign since 2004 that has led to more than 4,300 deaths.
That violence has been confined to the predominantly Muslim south of the country.
Matichon newspaper cited Maj. Gen. Srivara Rangsipramkul, acting police commander for Thailand's Central Region, as suggesting the room where the explosion occurred may have been used by a bombmaker.
The blast came on the same day that Thai authorities extended a state of emergency in Bangkok and three surrounding provinces, citing continued security concerns. The measure was imposed in April during the anti-government protests.
The authorities recently warned that stepped-up violence was expected beginning this month, and over the weekend detained 11 men in the northern province of Chiang Mai accused of training for armed attacks on behalf of a movement to overthrow Thailand's monarchy.
The claim has been met with skepticism by government critics, who feel it is being used to smear the so-called Red Shirt movement whose militant demonstrations earlier this year unsuccessfully demanded that Prime Minister Abhisit Vejjajiva call early elections. The Red Shirts in large part comprise followers of former Prime Minister Thaksin Shinawatra, who was deposed by a 2006 coup.
In Bangkok's worst bombing incident, eight separate bombs went off at locations around the capital the night of 2006-2007 New Year's Eve celebrations. Three people were killed and more than three dozen injured by the blasts, for which no one took responsibility or was brought to justice.
Thai security officials have a mixed record in dealing with explosives. Many have risked their lives to defuse bombs in the south placed by militants. But until last year, the army and other state agencies used a handheld device for locating explosives that has been exposed as a useless scam, as acknowledged by the government after testing.
In 2001, they made a major gaffe when they said that an explosion in a Boeing 737-400 jet that Thaksin, then prime minister, was supposed to board had been caused by a bomb, based on their supposed finding of traces of plastic explosive at the scene. The conclusion led Thaksin to initially claim he had been the target of an assassination attempt, perhaps by drug dealers irate with his government's crackdown on the illicit trade.
However, aviation experts later concluded that the blast was probably sparked from heated vapors in an empty fuel tank. One Thai Airways crew member was killed in the incident. (AP)