NEW : U.N. says rebel troops to adhere to cease-fire . thousands flee refugee camp in matter of hours . Doctors Without Borders says its peacekeepers still in charge of Congo . Goma says French forces join fight with minority Tutsi rebels .
NEW : U.N. says rebel troops to adhere to cease-fire . 45,000 flee refugee camp in matter of hours . U.N. says its peacekeepers still in charge of Goma . Congo says Rwandan forces join fight with minority Tutsi rebels .