TEHRAN (Agencies) - One hostage and three gunmen who held six Iranians captive in a restive southeastern region of the country have been killed in a rescue operation, the official IRNA news agency said on Saturday. Gunmen had attacked a bus on Thursday and seized six people - five soldiers and a bank clerk - between the towns of Iranshahr and Chabahar in Sistan-Baluchestan province. In a successful operation by the Revolutionary Guards, five of six hostages have been freed. One has been martyred and three of the culprits have been killed, Jalal Sayah, a provincial security official told IRNA without saying when this happened. The Sunni militant group Jundallah (Soldiers of God), in a statement on its website junbish.blogspot.com, claimed the attack, adding that it had killed a number of security forces during the assault. Jundallah, whose long-time leader Abdolmalek Rigi was executed in June, had threatened to kill the hostages unless its members currently held by Iranian authorities are released. Deputy Interior Minister Ali Abdollahi has rejected Jundallahs claim of the abduction. Jundallah says it fights for the interests of the southeastern provinces large ethnic Baluch community which follows the Sunni branch in mainly Shia Iran. The Baluch straddle the border with neighbouring Pakistan and Afghanistan. In the past decade, the group has taken responsibility for many deadly attacks on Iranian security forces as well as assaults that have led to civilian deaths. In July, it carried out twin suicide bombings at a mosque in the provincial capital Zahedan, reportedly targeting members of the Revolutionary Guards and killing 28 people. Sistan-Baluchestan is also known for drug trafficking, smuggling and tribal violence. Mehr quoted the commander of the Guards ground forces, Mohammad Pakpour as saying that some people were also injured in the incident. It seems that there is a remainder of the Rigi group whose purpose is to scare people and cause division in the area and to commit extortion, he said, referring to the former rebel leader, Abdolmalek Rigi, who was executed in June. Iran says Jundallah has links to the Sunni Islamist Al- Qaeda and in the past has accused Pakistan, Britain and the United States of backing Jundallah to create instability in the southeast of predominantly Shiite Iran. All three countries deny the accusation.