A renegade Thai general was shot in Bangkok on Thursday as the military planned to encircle the barricaded encampment of antigovernment demonstrators.
Khattiya Sawasdipol, 58, better known as Seh Daeng (Commander Red), was allied with the protesters. He was struck in the head by a bullet during an interview with an New York Times reporter, who took this photograph minutes before he was shot.
A protester was killed later during clashes. The army has moved to seal off the protesters’ large camp.
A state of emergency already in place in the capital and surrounding areas is to be extended to 15 other provinces.
All talk of reconciliation and election timetables has been abandoned and the Thai capital is braced for further bloodshed, said the BBC’s Rachel Harvey in Bangkok.
The US has closed its embassy in Bangkok saying it is “very concerned”.
The general, an incendiary figure who was in charge of security for the protesters, had been called a terrorist by the prime minister, who named him as the chief obstacle to a compromise plan to end a two-month sit-in here in return for an election in November.
The latest violence is the most serious since a failed crackdown in April that killed at least 25 people.
Commanding his own paramilitary force of former Rangers, the general was suspended without pay from the armed forces. A special committee was considering whether to strip him of his rank.
General Khattiya was part of the protesters’ more radical wing and had accused red-shirt leaders of not being hard-line enough.
The military had said it would start surrounding the protest camp at 1800 (1100 GMT) and advised people to leave.
Gunfire and an explosion were heard and there were reports of casualties. But it was not clear where the firing was coming from.
Earlier, a BBC reporter saw trucks unloading heavily-armed soldiers several blocks from the encampment.
Near the encampment, shops and businesses were urged to close before the deadline, and transport was suspended.
For more than two months, the protesters have been occupying parts of Bangkok (map, from bbc.co.uk). They want prime minister Abhisit Vejjajiva to dissolve parliament and call fresh elections.
According to the BBC’s Rachel Harvey, a column of about 200 soldiers had been seen moving towards the camp.
In the camp, street lights have been switched off which plunged parts of it into darkness. However protesters continue to defiantly blast out music, BBC correspondent says.
On Wednesday, the government announced a plan to cut off water and power supplies to the protesters, but then the plan was cancelled.