A group of miners from an unregistered union has been allegedly holding hundreds of their colleagues hostage since Monday morning.Members of the Association of Mineworkers and Construction Union (AMCU) reportedly refused to let their co-workers head to the surface at the end of their Sunday night shift.This is according to Jon Hericourt, the CEO of the New Kleinfontein Gold Mine company which manages the Modder East mine, outside the South African city Johannesburg.He believes 562 workers are trapped underground, with up to 120 of them being AMCU supporters who likely used hammers, picks, shovels and other mining equipment as weapons.Some 15 miners have reportedly been injured in scuffles, with one man sustaining a serious head injury.Mr Hericourt said negotiators had secured an agreement for a paramedic and security officer to be sent down and bring this man out on Monday, but these two were also taken hostage.