CAIRO (Update 1) - At least one person was killed and more than 20 were wounded in a sectarian clash in Egypt on Saturday over a Christian woman who had allegedly converted to Islam, officials said. The strife represents another challenge to Egypt's military rulers who are trying to restore law and order after President Hosni Mubarak was forced to step down in a popular uprising in February. Witnesses said the army and police deployed armoured vehicles to the Imbaba suburb of Cairo after some 500 Islamist Salafists surrounded a Coptic Church, demanding those in the church hand over the woman to them. Details were sketchy. The Salafists - conservative Islamists - and Christians exchanged gunfire and threw firebombs and stones at each other before the army and police arrived. Security forces fired tear gas to stop the clashes. The governor of Giza province told journalists at least one person died and 23 were wounded. It was not immediately clear whether dead and injured were Muslims or Christians.