BANGKOK, April 13 (Xinhua) -- A small bomb exploded at the Thai Constitutional Court early Monday morning, causing one security guard injured, Thailand's MCOT TV station reported.

    Three bombs were thrown into the court area around 03:30 a.m. (2030 GMT Sunday) with one exploded and damaged windows of the building and one of the unexploded bombs hit the leg of a security guard. The injured has been sent to hospital.

    Bangkok Metropolitan Police Chief Worapong Chiewpreecha rushed to the scene to inspect the loss, the MCOT said.

    The court, an independent one established under the 1997 Constitution, on December 2, 2008 dissolved then three ruling parties in the coalition government -- People Power Party (PPP), Chart Thai Party and Matchima Thipataya Party -- over charges of electoral fraud.

    On April 9, protestors led by the United Front of Democracy Against Dictatorship (UDD) known as the red-shirted people marched to the court, demanding all court members to resign for their ruling of dissolving the PPP.

    On Sunday afternoon, Thai Prime Minister Abhisit Vejjajiva abruptly declared a state of emergency in Bangkok and some districts in five nearby provinces, citing increasing danger of violence by anti-government protesters in the capital.