BANGKOK -- Thai soldiers and police fought pitched battles Saturday night with anti-government demonstrators in streets enveloped in tear gas, but troops later retreated and asked protesters to do the same. Fifteen people were killed and more than 650 wounded in Thailand's worst political violence in nearly 20 years. Prime Minister Abhisit Vejjajiva went on national television shortly before midnight to pay condolences to the families of victims, and indicated he would not bow to protesters' demands to dissolve Parliament and call new elections. "The government and I are still responsible for easing the situation and trying to bring peace and order to the country," Abhisit said, vowing a transparent investigation into the violence. The army had vowed to clear the "Red Shirt" protesters out of one of their two bases in Bangkok by nightfall, but the push instead set off street fighting. There was a continuous sound of gunfire and explosions, mostly from Molotov cocktails. After more than two hours of fierce clashes, the soldiers pulled back. Army spokesman Col. Sansern Kaewkamnerd went on television to ask the protesters to retreat as well. He also accused them of firing live rounds and throwing grenades during the fighting. An APTN cameraman saw two Red Shirt security guards carrying assault rifles. "The security forces have now retreated to a certain extent from the Red Shirts," Sansern said. He said a senior government official had been asked to coordinate with the protesters to restore peace. The Red Shirts' demonstrations are part of a long-running battle between the mostly poor and rural supporters of former Prime Minister Thaksin Shinawatra, and the ruling elite they say orchestrated the 2006 military coup that removed him from power. They see the Oxford-educated Abhisit as a symbol of an elite impervious to the plight of Thailand's poor and claim he took office illegitimately in December 2008 after the military pressured Parliament to vote for him. The government's Erawan emergency center said tallies from four Bangkok hospitals showed the death toll early Sunday had risen to at least 15 ��" four soldiers and 11 civilians.