NEW : hundreds people were killed , state media reports . The Muslim Brotherhood 's party says peaceful protesters were slain . Cairo 's The Muslim Brotherhood 's Egypt 's Interior Ministry said it had arrested 423 `` rioters '' on Sunday . says At least 51 of rioters were arrested . Demonstrators jump into the Old Cairo to escape arrest .
NEW : hundreds people were killed , state media reports . The Muslim Brotherhood 's party says peaceful protesters were slain . Cairo 's The Muslim Brotherhood 's says At least 51 of rioters were arrested . Demonstrators jump into the Old Cairo to escape arrest .