A Canadian woman was killed and several other tourists were taken hostage by gunmen who holed themselves up in a medieval castle in southern Jordan today after killing at least four police officers in a shooting spree.

Police in the mountainous city of Karak freed 10 people, including foreign tourists, but some were still being held in the Crusader-era castle from where the gunmen shot at security forces who were surrounding it, a security source said.

Prime Minister Hani al Mulki told parliament "a number of security personnel" had been killed and that security forces were laying siege to the castle. The Canadian government confirmed one of its nationals had been killed.

Police said the violence began when gunmen starting shooting at officers patrolling the town before entering the castle, perched on top of a hill.

The identity of the assailants was not immediately clear.

Jordan is one of the few Arab states that have taken part in a U.S.-led air campaign against Islamic State militants holding territory in Syria. But many Jordanians oppose their country's involvement, saying it had killed fellow Muslims and raised security threats inside Jordan.

Officials worry about radical Islam's growing profile in Jordan and support in impoverished areas for militant groups.