An army spokesman, Col Sunsern Kaewkumnerd, said about 400 soldiers had moved against some 300 protesters at the Din Daeng intersection.
Some protesters had responded by driving a car at the soldiers, he told AFP.
Col Kaewkamnerd was also quoted by Reuters as saying troops fired into the air first in response to tear gas and smoke bombs thrown at them by protesters, but "then fired real bullets".
"We will start with soft measures and proceed to harder ones," the army spokesman told AFP.
"We will avoid loss of life as instructed by the government."
BANGKOK (AP) -- Thai soldiers unleashed hundreds of rounds of automatic weapons fire to clear rock-throwing anti-government protesters from a major intersection in the capital in the pre-dawn darkness Monday.
Forty-nine people were reported hurt in the first serious clash between the two sides in ongoing protests that have roiled this southeast Asian nation and came a day after the country's ousted prime minister called for a revolution.
While the government has declared a state of emergency, protesters controlled many streets in the capital Bangkok. They had earlier commandeered public buses and swarmed triumphantly over military vehicles in defiance.
In the starkest example of the chaos, a mob of the red-shirted protesters smashed cars carrying Prime Minister Abhisit Vejjajiva and his aides.
The clash began between 4 a.m. and 5 a.m. Monday, as troops in full combat gear lined up and advanced to disperse the protesters, according to witnesses and television footage.
The soldiers fired hundreds of rounds from their M-16 automatic rifles as they advanced, though it was unclear whether they were firing at or over the protesters. Some witnesses said tear gas was also fired.
The official Erawan emergency coordination center said 49 people were injured on both sides and taken to hospitals.
The army seems to be blasting away.
You won't be reading any blood bath headlines in The Nation. Nor will you see the Queen going to any funerals.
The Reds are claiming a cover up. I have read at a couple websites that the mainstream media has been told to black out any contrary evidence to what the government is spouting.
The Reds have claimed that people have died. The military channels, Thai PBS, ASTV, and The Nation are covering up the truth.
I don't know what is going on because the servers are so damn slow and it takes forever to download a page.
If you have links, send them in.