enemy explosion during Time Freeze killed my friend in HC

A friend of mine had been running HC Chronomancer for a while. He was doing a map as usual and streaming while I was watching. He used Time Freeze in a Fortress map just casually walking and clearing, killing monsters as usual. All of a sudden he died during the time freeze, and after the Time Freeze effect expired, there were no monsters left alive on screen. We suspect that it was one of those big fat guys that grow red and explode after death that killed him at the time, but such a thing had never happened before during time freeze where an enemy or effect was allowed to take effect during it.