JAKARTA, Oct. 11 (Xinhua) -- Unidentified men launched a grenade attack on a car carrying businessmen in Aceh province Friday night, seriously wounding three people, provincial police spokesman Farid Ahmad said Saturday.

    The spokesman said that two men riding a motorcycle threw a grenade at a car, which carried contractors from Medan, the capital of nearby North Sumatra province.

    "The grenade attack injured three people," he told Xinhua from the province.

    Police were investigating the attack, said Ahmad.

    In mid-September, unidentified men struck an office of a political party with grenades, causing no casualties.

    For over three decades, oil-and-gas abundant Aceh province was caught in bloody conflicts that killed over 15,000 people, before a peace accord was signed between Jakarta and the separatist Free Aceh Movement or GAM in 2005 in Helsinki, Finland.