BEIRUT, Mar 22 (Reuters) At least 33 people were killed in an air strike that hit a school sheltering displaced people near Islamic State-held Raqqa, the Syrian Observatory for Human Rights said, and the US-led coalition was believed to have carried out the attack. Observatory activists had counted at least 33 bodies at the site of the strike near the village of al-Mansoura, west of Raqqa, Observatory Director Rami Abdulrahman told Reuters. The air strike took place on Monday night, he said. REUTERS AKC PM1341