Shocking moment ISIS militants take sledgehammers to Mosul tomb of Prophet Jonah as more than 50 blindfolded bodies are found massacred south of Baghdad
- ISIS militants filmed taking sledgehammers to tombstones in Mosul, Iraq
- Donning balaclavas and black clothing, they swung weapons into tombs
- One grave belonged to Prophet Jonah, revered by Muslims and Christians
- Rebels believe special veneration of tombs is against teachings of Islam
- Comes as more than 50 bodies have been found in city south of Baghdad
- Most of the bodies were blindfolded with gunshot wounds, said authorities
- Investigation is underway to establish the circumstances of the killings
