Thai troops fired live rounds and rubber bullets at charging anti-government protesters in a chaotic clash that killed a soldier and wounded 18 people on a congested highway in Bangkok's suburbs Wednesday. The troops had formed a roadblock to stop about 2,000 “Red Shirt” protesters who left their main protest site in central Bangkok's shopping district on pickup trucks and motorbikes in defiance of a state of emergency and despite repeated warnings. About 100 protesters had moved ahead of the main convoy, charging at security forces, who at first used batons and shields to push them back, witnesses said. Some red shirts hurled stones, shot metal balls from sling-shots and launched fireworks at the soldiers. Troops fired back with rubber bullets followed by live rounds, at first in the air and then narrowly over protesters' heads, as onlookers dashed for cover in cars and buses in the traffic-choked area 40 km north of central Bangkok, Reuters photographers and witnesses said. Three rounds of fighting finally stopped when a powerful tropical rainstorm drenched the area. By nightfall, troops had largely pulled out and many protesters returned to their 3 sq-km fortified encampment in central Bangkok. The state-run Erawan Medical Centre said at least 18 people were wounded and one soldier was killed. Witnesses said he was shot through his helmet, apparently caught in friendly fire. The fighting did nothing to end an impasse between protesters seeking elections and the embattled, military-backed government of Prime Minister Abhisit Vejjajiva – a seven-week crisis that has killed 27 people, wounded more than 900, paralysed Bangkok and hurt Southeast Asia's second-biggest economy. “The Red Shirts were testing the will of the security forces and now we saw that the government is getting serious about this,” said Somjai Phagaphasvivat, a professor at Thammasat University. “But it's hard to pronounce victory for either side from the incident today. There is still a lot of uncertainty.” The protesters began the day in high spirits, honking horns and singing as they headed for a market 50 km away in a rowdy, provocative procession. The violence stoked fears of more unrest ahead after grenade attacks last Thursday in Bangkok's business district killed a woman and wounded more than 80 people, and the military's failed attempt to disperse protesters on April 10 killed 25 people. The crisis is taking a deepening toll on Thailand's economy. Another three months of protests could shave 0.64 of a percentage point off Thailand's 2010 economic growth forecast of 4.5 percent, according to government forecasters.