Opposition fighters from Islamist brigades have killed at least 21 civilians and 20 pro-regime fighters in an Alawite village in Syria's Hama province, an NGO said on Monday.The Syrian Observatory for Human Rights, a Britain-based monitoring group, said fighters from Islamist brigades including Jund al-Aqsa were behind the deaths in Maan village, in central Syria, on SundayObservatory director Rami Abdel Rahman said there were no immediate details on how the civilians had been killed, but added that at least 10 of them appeared to be from a single family.The group said at least 20 members of the National Defence Forces, a pro-regime militia, had been killed in the attack.