Troops, firing shots into the air, have apparently retaken control of the Din Daeng intersection from red-shirted protesters, according to TV news reports. There were reportedly some injuries but no immediate reports of death.
At least 77 people suffered minor injuries, many from tear gas, according to hospital reports. About five persons were seriously injured. The red-shirted movement claimed "several" of its members suffered gunshot wounds, and condemned the authorities' use of live bullets in the crackdown.
TV news footage showed soldiers firing shots into the air. Tear gas was also fired, TV reporters at the scene said. A few hundred troops were involved in the operation.
At around 7.20 am, the government announced it was in control of the situation at Din Daeng.
The clash took place around 4 am and left about 50 soldiers and protesters injured, it was reported. Gunshots were still heard after 5 am, but not as intensely as when the crackdown began.
One TV reporter quoted "runaway" protesters as saying that there might have been some deaths. The government reported no death.
The troops were pushing from the Din Daeng intersection toward the Victory Monument. Protesters were scattered and retreated from the intersection to the moment. It appeared that the troops were in almost complete control of the Din Daeng intersection after 6 am.
Col Sansern Kaewkamnerd, Army spokesman, said 300 protesters were in the area when security forces including soldiers and police moved in. He said the troops first tried to negotiate with the protesters, who were allegedly armed with molotov cocktails and tear gas themselves.
He said the talks broke down after some protesters tried to ram buses against the troops.
"The troops had to fire into the air. I repeat. They fired into the air and took action against the protesters," he said.
Some arrests were made, he said, adding that "reluctant participants" of the protest who were forced to stay by fellow protesters were released.
"Similar operations will be carried out in other areas," he said.
Protesters have burnt tyres on a few spots in the Din Daeng area, and there have been concern that red-shirted protesters would resort to arson in response to the crackdown.
Several intersections were still occupied Sunday night by the protesters, who used buses to barricade several major roads, spawning massive traffic jams. Police said up to 30,000 demonstrators were scattered around the city. Police vans at some intersections were abandoned and looted, AP reported.
Protest leaders have woken up red-shirted demonstrators at Government House to inform them of the Din Daeng incident and tell them to prepare themselves for a possible crackdown.
Gunshots at Din Daeng intersection could still be heard around 5 am, but not as intense as an hour earlier. TV footage showed some wounded protesters taken into military vehicles.
Earlier, Prime Minister Abhisit Vejjajiva has assured the nation that there is no disharmony within the government as well as key agencies responsible for enforcing law and order.
In a late-night television address, Abhisit was flanked by all key government, military and police leaders, a setting apparently intended to stamp out persistent speculation that he was losing support of top police and military officers.
He said the rumours were intended to weaken the government which has been trying to restore law and order through peaceful means.
"There have been a lot of rumours and I would like the Thai media to report on the truth to the Thai public," he said.
Among false reports, he said, were claims that security forces had already resorted to violence to suppress the red-shirted protesters.
The prime minister insisted that a united government remained confident that the situation would improve in the next few days.
Abhisit had vowed not to bow to the red-shirted protesters' demand for him to either step down or dissolve the House, and expressed confidence that the military and the police, whom he had reportedly criticised in private, were still firmly on his side. It had been reported that Abhisit singled out police chief Patcharawat Wongsuwan for sharp criticism following Saturday's collapse of the Asean summit with dialogue partners.
Coup rumours were intense late Sunday afternoon but seemed to subside late into the night. Speculation now was focused on when security forces would move against protesters occupying some key areas in the city.