Rescue workers search for victims at Bento Rodrigues district witch was covered with mud after a dam, owned by Vale SA and BHP Billiton Ltd burst, in Mariana, Brazil, on Sunday. So far two people were confirmed dead. As many as 28 people are still missing after two dams burst on Nov 5, triggering the disaster and prompting a rescue and salvage operation involving about 500 people, many of whom are still searching, with the help of dogs and special equipment, for victims along the floodplain downstream from the dams. Neither authorities nor mine operator Samarco - a joint venture between the world's largest mining company, BHP Billiton Ltd, and the biggest iron ore miner, Vale SA - have determined a cause for the rupture. Ricardo Moraes / REUTERS