CAIRO (Updated) - Hundreds of Christian Egyptians clashed with police in Cairo Wednesday and seven police officers were injured in a protest against the shooting to death of a Christian man by a Muslim policeman on a train. Some 500 Christians demonstrating against Tuesday's shooting blocked two main highways pelting vehicles with stones, a security source said. Police trying to disperse the crowd clashed with the protesters, who also stoned the police, wounding two senior officers and five other policemen. Twelve protesters were arrested, the source added. Christians make up a tenth of Egypt's 79 million people and have long complained of unfair treatment. They have accused the government of not doing enough to protect them. Tuesday's fatal shooting is likely to stoke tensions in the Muslim majority country, where Christians protested for several days after the January 1 bombing of a church in Alexandria that killed up to 23 people, political analysts said. But Egyptian authorities Wednesday denied Tuesday's attack was sectarian, saying the policeman who shot the Coptic man was not religiously motivated.