BANGKOK  Thailand’s political crisis worsened Tuesday when antigovernment protesters trapped lawmakers inside the Parliament building and fought running battles with the police that left one person dead and nearly 400 injured.

The army was deployed on the streets of Bangkok after the worst political violence since 1992 as protesters continued a six-week sit-in outside the prime minister’s office, forcing the government to conduct its business from a former international airport.

Prime Minister Somchai Wongsawat asserted that he would not step down, and the military repeated a promise not to stage a coup, while the protesters said they would continue their actions until they brought down the government.

They accuse the ruling party of being an extension of the rule of former Prime Minister Thaksin Shinawatra, who was elected on a populist program in 2001 and ousted in a coup in September 2006. He now lives in London but continues to exert influence among his allies here.