Gunmen have opened fire on an anti-government rally in eastern Thailand, killing a five-year-old girl and wounding dozens of other people.Attackers threw explosives and shot at demonstrators at a rally called by the People’s Democratic Reform Committee.The incident took place at a night market in the Khao Saming district of Trat province late on Saturday.Tensions across Thailand have escalated since a wave of anti-government protests began in November.The demonstrators want Prime Minister Yingluck Shinawatra to resign to make way for an appointed interim government, but she has refused.On Tuesday several people were killed in clashes that erupted in Bangkok, when police began clearing protest sites. The latest attack occurred about 300km (180 miles) south-east of the capital.Officials said the five-year-old girl had been standing at a noodle stall when the attackers, in two pick-up trucks, opened fire at the PDRC rally. She died from a gunshot wound to the head.PDRC spokesman Suwicharn Suwannakha said the attack happened during a speech by a party leader, Thai newspaper The Nation reported. He said he first heard the explosions and gunfire and then saw chairs in front of the stage scattered.”It was chaotic. I saw two pick-up trucks speed away,” he said. No group has so far said it carried out the attack.But the BBC’s Jonathan Head in Bangkok says suspicion will fall on armed groups on the fringe of the so-called “red shirt” supporters, who back Ms Yingluck.Over the past two months there have been several attacks on protesters’ camps in the capital, he says, but these sites are now well-guarded by the protest movement’s own armed wing.There has been growing frustration recently from the red shirts over the government’s inability to disperse the protesters, who have been occupying parts of central Bangkok for weeks, our correspondent adds.Red-shirt leaders have organised a mass gathering in north-eastern Thailand this weekend to decide how they should fight back against the campaign to unseat the government.Ms Yingluck heads a government that won elections in 2011 with broad support from rural areas.The anti-government protesters want her government to be replaced by an unelected “people’s council” to reform the political system.They say that Thailand’s democracy has become corrupted and that Ms Yingluck is controlled by her brother, ousted leader Thaksin Shinawatra.In response to the protests, Ms Yingluck called snap elections on 2 February, which her government was widely expected to win.