An explosion near Thai capital Bangkok's international airport Monday left a plastics factory in flames, killing at least one firefighter and wounding 29 people, officials said.
Heavy plumes of black smoke could be seen rising up to the sky from the city's downtown 35 kilometres (21 miles) away, as helicopters continued to dump fire suppression foam from the air on the site.
The blast occurred around 3 am at Taiwan-based Ming Dih Chemical Co., located on the outskirts of Bangkok near Suvarnabhumi airport.
By noon, 500 residents near the area were moved to two shelters, including a nearby school about 9 kilometres away, where elderly residents in wheelchairs waited to return to their homes.
Rescue workers drove around surrounding neighbourhoods in emergency vans, telling thousands of residents via loudspeakers to leave for their safety.
The public have been ordered to stay away from a radius of at least 500 metres around the blast site, said Lieutenant General Ampon Buarubporn.
"We do not know if there is anything left to explode," he said, adding that authorities are still working to get the fire under control.
The cause of the explosion is still unknown.
Air quality
According to officials, Ming Dih Chemical Co. produces expanded polystyrene — colloquially known as styrofoam — and has been in operation since 1985 in Bang Pli district.
Besides being the site of Suvarnabhumi airport — which saw massive black clouds above its airport runways Monday — the 500-metre radius around the factory is also home to some 300 factories and residential neighbourhoods housing 240 communities.
"We have sent air quality vehicles to check the air around the area and will work together with the pollution control department," said Industrial Minister Suriya Juangroongruangkit.
Around 5 pm — 15 hours after the pre-dawn explosion — the fire was still raging and sending billowing clouds of smoke into the sky.
Multiple fire trucks, water trucks and two helicopters were deployed to quell the blaze, which left a wreckage of debris and gnarled metal beams.
"Two flights carried 6,000 tons of firefighting foam to put out the fire," said deputy interior minister Niphon Boonyamanee.
"We are supporting the operation with our full capacity so the situation will be in control as soon as possible."
Traffic around the area was thrown into chaos as authorities closed a main road running parallel to the airport, while strong fumes of burning plastic permeated the area.
Thitipong Choke-umnuay, whose workplace is about 10 kilometres away from the factory and escaped the impact, said his family members living closer were not so lucky.
His aunt had evacuated to his office after the impact of the explosion caused severe damage to her home.
"Today she will move to my house in Lat Phrao (in central Bangkok), because she can't live at her house," the customs clearance agent told AFP.
"It's a chemical explosion so there are strong smells.