BANGKOK (Reuters) -- Thai troops fired repeatedly into the air in Bangkok on Monday after anti-government protesters torched a bus at a main junction, forcing the demonstrators to pull back, a Reuters reporter said.

When troops tried to put the bus blaze out with a water cannon, the protesters threw a volley of five or six fire-bombs at them, and the soldiers advanced in response to that.
The clashes, two days after protesters forced a cancellation of an Asian summit, have undermined confidence in the government and dealt another blow to the image of an economy already reeling from last year's political chaos and the global financial crisis.
“I believe the darkest days in Thailand's history are yet to come, as we see no swift solution to ongoing divisiveness,” said Prinn Panitchpakdi, a CLSA Asia-Pacific analyst.
Bangkok Medical Center director Peeraphong Saicheau said 77 people were injured in clashes at the junction, which began just before dawn. Two civilians and two soldiers had gunshot wounds.
A number of protesters had been arrested, said Army spokesman Colonel Sansern Kaewkamnerd.
Sansern said the fracas began when troops in vehicles with loudspeakers asked the red-shirted protesters to lift a blockade they have maintained for days at Din Daeng junction.
The junction is a crucial part of Bangkok's traffic system, although Monday is the start of a three-day holiday for the Thai New Year and many people have already left for the provinces. Financial markets are shut until Thursday because of the holiday.
Troops had rolled up water cannon and demonstrators had covered the road in petrol, apparently threatening to set it ablaze if troops moved in -- which they did when the “red shirts” set the bus ablaze.
Protesters had commandeered an LPG tanker near the junction. “We won't leave. We want real democracy,” said one “red shirt” standing at the junction where protesters had driven six public buses to create a roadblock. “We're not scared of the army,” said the man who gave his name as Wi.
But the Reuters reporter said troops succeeded in pushing the protesters out of the Din Daeng junction, chasing after them and firing into the air. Soldiers detained several protesters, stripping them of their red shirts.
Fires blazed in the street and plumes of smoke rose from burning tires during the morning standoff between troops and protesters. Ambulances and firetrucks were on standby.
A Buddhist monk with a megaphone stood in the intersection pleading for calm and telling the soldiers: “Don't shoot, think about your country.” Police on motorbikes shuttled between troops and demonstrators to mediate.
Prime Minister Abhisit Vejjajiva declared a state of emergency in Bangkok on Sunday after red-shirted supporters of former prime minister Thaksin Shinawatra forced the cancellation of the Asian summit in the southern beach resort of Pattaya.