RIO DE JANEIRO - At least 34 people were killed, and hundreds remain missing after a tailings dam owned by mining giant Vale collapsed Friday afternoon in Brazil's southeastern state of Minas Gerais, the state fire department said.

A total of 46 people were rescued on Saturday morning. And 23 of them were injured and taken to local hospitals.

It is estimated that there are at least 252 Vale workers unaccounted for, according to the company, while the number of local residents who have yet to be found remains unknown.

Civil defense officials said there is still hope to find survivors, as helicopters have found some places which were possibly used as shelters.

However, rescue works may have to be temporarily suspended as it started to rain in Brumadinho, a municipality of Minas Gerais, diminishing chances of finding survivors.

Vale has received an initial fine of 250 million reals ($66 million) imposed by Brazil's environment protection agency Ibama.

The Brazilian government has promised a full investigation into the matter. President Jair Bolsonaro and Minas Gerais state Governor Romeu Zema flew over the destroyed region earlier in the day and promised manpower to aid the rescue, and resources to help the region recover.

In November 2015, a tailings dam collapsed in Mariana, Minas Gerais, killing 19 people and causing substantial environmental and economic damage. It was considered the worst environmental disaster in the Brazilian history.