Thousands of supporters of Thai Prime Minister Yingluck Shinawatra meet on Sunday hours after an attack on an anti-government rally killed at least two people and wounded 41, police said, raising tension in the country's protracted political crisis.
Gunmen shot at a protest stage and threw explosive devices in the Khao Saming district of the eastern province of Trat on Saturday evening, police said.
"At least two people were killed, but the number of dead is not definite and it could be more," police spokesman Kissana Phathanacharoen told Reuters.
"Forty-one people were hurt. Explosive devices were used but we can't confirm what type as the bomb disposal team is still investigating."
Among the seriously wounded was an eight-year-old girl, who suffered a shot to the head, the Bangkok Post said.
Anti-government protesters have blocked main Bangkok intersections for weeks with tents, tyres and sandbags, seeking to unseat Yingluck and halt the influence of her billionaire brother, Thaksin Shinawatra, an ousted former premier regarded by many as the real power behind the government.
Presenting a further headache for Yingluck, Thailand's anti-corruption body filed charges against her last week over a rice subsidy scheme that has left hundreds of farmers, her natural backers, unpaid.
Yingluck is due to hear the charges on Thursday.
The United Front for Democracy against Dictatorship, a protest movement largely made up of "red shirt" Thaksin supporters based in the populous north and northeast, is holding a meeting of its leaders from across the country on Sunday in Nakhon Ratchasima, northeast of the capital.
Chairwoman Thida Tawornseth said Sunday's rally would consolidate plans to restore democracy after the opposition boycotted and disrupted elections this month, leaving the country paralysed under a caretaker government. She ruled out any plans for violence.
"If we wanted to clash, we would have done so a long time ago," she said on Saturday. "We wouldn't have to wait for this long."
Four protesters and a police officer were killed on Tuesday when police attempted to reclaim protest sites near government buildings. Six people were wounded by a grenade on Friday.
Thailand's King Bhumibol Adulyadej has intervened in previous political standoffs but the 86-year-old monarch has not commented publicly on the current impasse.
Thaksin's enemies accuse him of republican aspirations, a charge he has frequently denied.