KADUNA, Nigeria: Police in northern Nigeria have arrested hundreds of people after deadly protests in opposition strongholds in the mostly Muslim north following President Goodluck Jonathan's election victory. At least 80 people have been killed in major cities alone, hundreds injured and thousands displaced by the violence after Jonathan won Saturday's vote. His rival, northerner and ex-military ruler Muhammadu Buhari, says the result was rigged. Those perceived to be supporters of the ruling party have been stabbed, hacked and shot to death by angry youths since Jonathan, a Christian southerner, defeated Buhari. Churches, mosques, homes and shops have been set ablaze. The morgue at the Bara Dikko hospital in the city of Kaduna was overflowing. It had 20 bodies in its cold chambers. The charred remains of at least another 20 lay on the floor. Kaduna's deputy police commissioner, Nwodibo Ekechukwu, said hundreds of people had been arrested. “We're talking of over 400 suspects. They are in police custody. They were arrested for various acts of mischief, criminality and homicide,” he said. Police further north in Kano, the region's most populous city, said at least 50 people were arrested there. Health workers collected blackened corpses in the streets of Kaduna on Tuesday, one of them apparently “necklaced” with a flaming tyre. A mosque was still burning, and the remains of tyres and barricades littered the streets. Ekechukwu said the security situation was gradually improving and that a 24-hour curfew was being reviewed on a daily basis. Soldiers manned checkpoints every few hundred metres in parts of the city. But there was also unrest in smaller towns where the military presence was not so heavy. The burned out shells of trucks and cars lay along the 200 km (120 mile) stretch of road between Kano and Kaduna, a Reuters witness said. Police in Bauchi state said four members of the National Youth Corps, which helped run elections, and two policemen were killed in an attack on Tuesday while the head of the local Christian association said 10 of its members were killed.