DAMASCUS, Syria -- An explosion ripped through a busy intersection in the Syrian capital Friday, hitting a bus carrying police and killing up to 25 people in what Syrian authorities said was the second suicide attack in as many weeks.

The bus was left riddled with shrapnel, blood splattered on its seats and pooled on the asphalt of the street after the blast, which came exactly two weeks after twin bombings targeting intelligence agencies in the capital killed 44 people. The bombings mark a dramatic escalation of bloodshed as Arab League observers tour the country to investigate President Bashar Assad's bloody crackdown on a 10-month-old popular revolt.