NEW : more than 200 people are killed across U.S. on Thursday , opposition activists say . U.N. monitors arrive in Tremseh and find evidence of an attack . An opposition group says At least 73 people were killed there Thursday . The Syrians government blames the Tremseh incident on armed terrorist groups .
NEW : At least 73 people are killed across Syria on Saturday , opposition activists say . U.N. monitors arrive in Tremseh and find evidence of an attack . An opposition group says more than 200 people were killed there Thursday . The Syrian government blames the Tremseh incident on armed terrorist groups .