PowerPoint Show by Andrew

On November 5, two dams retaining tons of iron-mining waste near the Brazilian town of Bento Rodrigues burst, releasing a massive flood of thick, red toxic mud that flattened buildings and trees, smothered the small town, killed at least four, and left another 28 still missing.

The dams are operated by the mining company Samarco, which is jointly owned by two larger mining companies: Vale, from Brazil and BHP Billiton, from Australia. Rescue workers are still searching for survivors as both Samarco and Brazilian authorities have issued statements saying the cause and full extent of the disaster remain undetermined.

Aerial view of damage after a dam burst in the village of Bento Rodrigues, in Mariana, Minas Gerais, Brazil, on November 6, 2015.

View of damages after a dam burst in the village of Bento Rodrigues, in Mariana, Brazil, on November 6, 2015.

A rescue worker touches the face of a horse which was covered with mud.

Trees covered with mud are pictured in Mariana, Brazil, on November 6.

A rescue worker observes the destruction of Bento Rodrigues.

Inhabitants and volunteers clean a street in Barra Longo, 60 kilometers from Mariana, Brazil, on November 7, 2015.

Rescue workers search for victims on November 8, 2015.

A dog sits in a destroyed house in Bento Rodrigues, on November 8, 2015.

Rescue workers walk at the site where the town of Bento Rodrigues stood after two dams burst in Minas Gerais, Brazil, on November 8, 2015.

Brazilian firemen rescue a foal which remained next to its mother after a dam burst in the village of Bento Rodrigues, on November 6, 2015.

Firemen rescue the foal which was trapped in the mud on November 6, 2015.

A truck hangs upside down on November 6, 2015.

An electricity worker attempts to cross a flooded area in Barra Longa, on November 7, 2015.

A rescue worker walks between destroyed houses in the town of Bento Rodrigues, on November 8, 2015.

Rescue workers search for victims in Minas Gerais, Brazil, on November 8.

Rescue workers take a break from their search for victims in the town of Bento Rodrigues, on November 8, 2015.

A survivor leaves a police car in Bento Rodrigues, on November 8, 2015.

Jaqueline da Aparecida Fernandes shows the picture of her brother Mateus, 29, who is missing in Mariana, Brazil, on November 7, 2015.

People carry an injured dog they rescued from the flooded town of Bento Rodrigues on November 7, 2015.

A bicycle covered in mud is seen in a street of Barra Longo, 60 km from Mariana, Brazil, on November 07, 2015.

Horses struggle in the mud in the flooded town of Bento Rodrigues on November 6, 2015.

A man works on the cleaning of a house flooded with mud after the dam burst on November 7, 2015.

Aerial view of the small town of Bento Rodrigues after the dam burst on Thursday in Minas Gerais, Brazil, on November 6, 2015.

A rescue worker covered in mud searches for victims at Bento Rodrigues, after two dams burst on Thursday, in Minas Gerais, on November 8, 2015.

A chicken walks on a cable in Bento Rodrigues, on November 8, 2015.