BANGKOK, Thailand (CNN) -- A grenade apparently fired into a gathering of anti-government protesters camped out in the Thai prime minister's office compound killed one person and wounded 23 others Thursday, officials said.

It was the first fatal assault inside the compound since supporters of the People's Alliance for Democracy (PAD) seized Government House in August.

The grenade, fired early Thursday morning, landed in one of the many tents that protesters have set up inside the premises as they continue their movement to unseat the democratically elected Thai government, authorities said.

A military official, who is also a PAD member, inspected the explosive and said it appeared to have been fired from an M-79 grenade launcher.

While the death was the first inside the compound, others have been killed in mass street demonstrations organized by PAD.

Two people died in October when Thai police clashed with thousands of PAD protesters who barricaded Parliament and prevented lawmakers from leaving. More than 420 were wounded in those clashes.

A month earlier, another person was killed in police-protester clashes.

Don't Miss Blog: Descent into chaos

The anti-government alliance accuses the current administration -- led by the People Power Party (PPP) -- of being a proxy government for former Thai Prime Minister Thaksin Shinawatra. Thaksin was ousted in a bloodless coup in 2006, but he returned to Thailand after the PPP swept into power in December 2007.

But Thaksin fled again in August just as he was to appear in a corruption case against him. The anti-government protesters want him extradited and tried on those charges.

The opposition also accuses the PPP government of wanting to amend the constitution so Thaksin does not have to face prosecution.

The protesters have held almost-daily demonstrations since May and have fortified Government House with sandbags, tires and shells of burned-out buses. Read Dan Rivers' blog on Thailand's descent into chaos

In September, the protesters accomplished one of their goals when Thailand's Constitutional Court stripped then Prime Minister Samak Sundaravej of his post, ruling that he had violated the constitution by appearing as a paid guest on a television cooking show.

The PPP responded by picking Thaksin's brother-in-law to replace Samak -- a move that further inflamed the protesters, who have continued their campaign.

CNN's Kocha Olarn contributed to this report

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