By the Associated Press

SAO PAULO (AP) — Eight employees of Brazilian mining giant Vale have been arrested in connection with the investigation into last month’s collapse of a mining dam that killed at least 166 people and left 147 missing in the southeastern state of Minas Gerais.

The state’s prosecutor’s office said in a statement that the employees were arrested Friday.

They will be held “under temporary custody” for 30 days to determine whether they have responsibility for the Jan. 25 collapse.

Those arrested include four managers and four members of technical teams in charge of monitoring the stability of the dam located near the city of Brumadinho.

Brazil research institute Fiocruz recently said the contamination of the ecosystem and the Paraopeba River could precipitate the spread of dengue, yellow fever or diarrhea in the area.