N’DJAMENA, Chad (AP) — Rebels seeking to overthrow Chad’s new transitional government are claiming to have shot down a military helicopter and say they now control the northern town of Nokou. It was not possible to independently confirm the allegations by the armed group known as the Front for Change and Concord in Chad. A rebel spokesman accused the military of carrying out aerial bombardments and said the militants had shot down one helicopter in the north. Meanwhile, the spokesman for the transitional military government urged opposition protesters to avoid violence amid renewed calls for demonstrations. Unrest in the capital, N’Djamena, left at least six people dead on Tuesday.