Thai security forces and anti-government protesters remained in a stand-off in Bangkok after clashes overnight in which one person died.
Shots and bangs were heard overnight as security forces moved to cut power and seal off access to the large protest camp in the city centre.
Earlier, a renegade general supporting the protesters was shot by an unknown gunman and is in a critical condition.
The protesters want Prime Minister Abhisit Vejjajiva to step down.
Streets which would normally be full of commuters were almost empty early on Friday, says the BBC’s Vaudine England in Bangkok.
Thousands of protesters, known as red-shirts after the colour they favour, have reinforced their barricades and vowed to maintain their camp in a commercial district of Bangkok until elections are called.
“The total seal-off measure took place since yesterday evening,” army spokesman Col Sunsern Kaewkumnerd said.
“Metropolitan Electricity Authority has cut off the power around Ratchaprasong intersection last night,” he said.
The authorities have also begun to cut public transport and some mobile phone service to the area occupied by the protesters.