TWENTY Iraqi detainees and a warder were killed today in a failed breakout from a Baghdad prison, an interior ministry official said. Prisoners stole a weapon from a guard at an Iraqi detention facility in the northern Shiite pilgrimage district of Kadhamiyah, before shooting dead one prison officer and wounding another. Guards then opened fire on the detainees, killing 20, the official said. Many of those detained at the facility are held on terrorism charges.