BANGKOK (AP) — Hundreds of riot police attempted to clear out anti-government protest sites around Thailand's capital on Tuesday, triggering clashes that left four people dead and 64 others injured.

Multiple gunshots were heard near the prime minister's offices, where riot police had started to remove protesters and dismantle a makeshift stage. Witnesses said shots were fired by both sides. Police later withdrew.

In another blow for Prime Minister Yingluck Shinawatra, the state anti-corruption agency accused her on Tuesday of improperly handling an expensive rice subsidy scheme, putting her in jeopardy of being impeached.

The National Anti-Corruption Commission said Yingluck's government proceeded with the scheme despite advice from experts that it was potentially wasteful and prone to corruption. The government has been months late in making payments to farmers for the rice they pledged to sell at above-market prices.

The commission said Yingluck has been called to formally hear the charges on Feb. 27. If it decides to submit the case to the Senate for possible impeachment, Yingluck will immediately be suspended from performing her official duties pending a Senate trial.

Yingluck's elected government has been attempting to avoid violence to keep the powerful military from stepping in. Thailand has been wracked by political unrest since 2006, when Yingluck's brother, former Prime Minister Thaksin Shinawatra, was ousted by a military coup after being accused of corruption and abuse of power. Since then, his supporters and opponents have vied for power, sometimes violently.

Erawan emergency medical services said three civilians and a police officer died and 64 others were injured in Tuesday's clashes, including a journalist working for Hong Kong's Phoenix TV.

Department of Special Investigation chief Tharit Pengdit told a news conference that the protesters had launched grenades at the police.

The violence erupted after police moved into several locations around the city to detain and remove protesters who have been camped out for weeks to press for Yingluck's resignation. They want the formation of an unelected people's council to implement reforms to end corruption and keep the Shinawatra family out of politics.

They have blocked access to government offices since late last year and occupied key intersections around Bangkok for about a month. Until now, the police had refrained from dispersing them for fear of unleashing violence.

But on Monday, the government's special security command center announced it would reclaim five protest sites around the city for public use, a move made possible under a state of emergency declared in January. Thousands of police officers, including armed anti-riot squads, were deployed across the city Tuesday in an operation the government called "Peace for Bangkok."

Earlier Tuesday, 144 protesters near the Energy Ministry in the northern part of the city were peacefully detained and herded onto police trucks to be taken away for questioning, Tharit said.

Transport Minister Chadchart Sittipunt told The Associated Press the protesters hijacked two of the city's public buses and used them to block a rally site at the Interior Ministry near the Grand Palace.

The operations came a day before the Civil Court is to rule on the government's invocation of the emergency decree, which allows authorities to exercise wide powers to detain protesters and hold them in custody for 30 days without charges.

If the decree is struck down by the court, the government will be forced to dismantle the special security command center it had set up to enforce the emergency measures.

The ongoing rice scandal has created tumult in state banks, from which the government is seeking loans to pay off money owed to farmers. A deal to have the Bank for Agriculture and Agricultural Cooperatives borrow as much as 20 billion baht ($625 million) from the Government Savings Bank was scuttled after a run on the savings bank by depositors sympathetic to the anti-government cause.

The savings bank requested the return of 5 billion baht ($156 million) already loaned, and its president resigned Tuesday to take responsibility for the situation.

Since the protests began in November, at least 15 people have been killed and hundreds injured.

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Associated Press photographer Wally Santana and television journalist Chalida Ekvitthayavechnukul contributed to this report.