In Nigeria, authorities have ordered a 24-hour curfew in the central city of Jos after fighting resumed between gangs of Christian and Muslim youths. At least 20 people are reported to have been killed since Sunday. <br/><br/>Gunfire has been heard, while smoke is rising from burning buildings. Residents say many buildings have been set on fire, especially in the northern parts of the city. According Nigerian Red Cross official at least 3,000 people have fled their homes. <br/><br/>Extra troops have been deployed to the area, which has seen several bouts of deadly violence in recent years. At least 200 people were killed in clashes between Muslims and Christians 2008, while some 1,000 died in 2001.