At least six people were killed and 31 injured on Friday in a suicide bomb attack at a mosque here, a police source said.A suicide bomber detonated his explosive vest among dozens of worshippers attending the Friday weekly prayer at a Shiite mosque in the suburb of Radwaniyah, the source told Xinhua news agency on the condition of anonymity.The massive blast also caused severe damage to the mosque, the source said.The toll could rise as ambulances, police and civilian vehicles were evacuating the victims to nearby hospitals and medical centres, the source added.