LAGOS (Reuters) - Up to 50 people were killed in weekend clashes between Nigeria‘s dominant Hausa and Yoruba tribes near the commercial capital Lagos, local newspapers said on Monday. Witnesses in Shagamu, 30 km (18 miles) from Lagos, told Reuters that at least 25 people died in the fighting which erupted after the killing last week of a Hausa woman who was caught watching Yoruba rites. "About 70 buildings including shops, mosques, a hospital and hotels were razed," said the independent Vanguard newspaper. Scores of riot police moved into Shagamu on Sunday to prevent any further violence between heavily armed mobs from the two biggest of the more than 200 ethnic groups in the West African country of 108 million. The Hausa trading community from Moslem northern Nigeria has been established in Shagamu for at least a century. Ethnic clashes are frequent in Nigeria but those between Hausas and Yorubas have gained added significance since the end of 15 years of Hausa-dominated military rule on May 29, when elected President Obasanjo, a Yoruba, took office.