Philippine police have arrested 49 people suspected of attacking officers in violent clashes near the president palace. The violence erupted Sunday as over 33,000 people elsewhere in Manila protested peacefully a corruption scandal involving lawmakers and officials accused of taking kickbacks from flood-control projects. The melee outside the presidential palace involved about 100 people and left around 70 officers injured. Police used tear gas to disperse the attackers, who vandalized property and carried black flags. Authorities have yet to identify the attackers and it remains unclear if they participated in the earlier peaceful protests.