Rescue organisations race to be first to traffic smashes
In the cramped offices of Bangkok's premier rescue organisation, the crackle of a short-wave radio signals the first emergency of the night.
A sick woman needs urgent transfer to hospital. The operator orders a rescue team to the scene.
In a city virtually bereft of public emergency services, the Por Tek Tung and smaller groups like the Ruam Katanyoo fill the gap.
Their converted Toyota pick-ups circle the streets day and night, jostling to be the first to bring assistance to victims of tragedy and violence.
Not for nothing are they known as Bangkok's "body-snatchers", so called because of their eagerness to save bodies, and therefore souls, as a way to earn Buddhist credit.
Tonight's dose of misery is particularly heart-rending. On the banks of the Chao Phraya river, grief-struck relatives watch as Por Tek Tung scuba divers recover the bodies of three young schoolgirls drowned in a boating accident.
Routine fare
For veterans like Somsak Boonchu - with 15 years' experience behind him - sudden death in all its many forms is routine fare. Murders, suicides, collapsed buildings - he has witnessed them all.
"Some people might be appalled by such work", he admits. "But they forget that we do it for the good of society."
Unsurprisingly it is the lethal mayhem of Bangkok's congested streets that keeps the "body-snatchers" busiest.
Hauling mangled corpses from car wrecks, though, is a far cry from the Por Tek Tung's original vocation.
Today it runs a hospital and other services from public donations.
That apart, very little is known about how these undeniably professional but rarely accountable groups operate.
Magazine publisher and long-time Bangkok resident Colin Hastings says the air of mystery surrounding the "body-snatchers" makes many people wonder about their motives.
Financial questions
"These particular services do a good job here. But there's been over time some questions over their financing, and who's actually behind the organisations," says Hastings.
Even so, he acknowledges: "They've always managed to do a very efficient job in getting to the scene quickly and taking initial care of people in dire circumstances."
Worshippers who come to burn incense and make offerings at the Por Tek Tung's temple in central Bangkok are the organisation's main source of income.
Pious Buddhists believe that by donating to charities that care for the sick and the dead, they earn spiritual credit for themselves - credit that will serve them in the afterlife.
Benefactors tend to give more generously to the group that rescues the most victims - a fact that has led to an unhealthy element of competition between the Por Tek Tung and its rivals.
There have been occasions when competing groups have come to blows while trying to rescue the same victim.
Back at headquarters, more emergency calls are coming in; a busy night for the rescue teams lies ahead.
The cynics who accuse the "body-snatchers" of exploiting other people's misfortune for profit may have a point.
But it is equally hard to deny that without them, Bangkok's streets would be a far more hazardous place.