Probably a combination of the the “rescuers” being less worried about hostage survival than perpetrator escape.
Some of the few people who managed to get out (they were hiding in the complex) said that the kidnappers killed all the hostages when they realized they couldn’t escape. Some of them were shot and I guess others were blown up, hence the disfigurement.
Yeah both the terrorists and the “rescuers” considered the hostages “Kaffir”...