A dam collapse in Southeastern Brazil last month has left the region with upwards of 300 casualties and countless missing persons reports. But some people think this accident could have been prevented.

On the 25th of January near Brumadinho, a dam owned by the Brazilian mining company Vale burst, which caused 2.5 billion gallons of muddy water to flood into the surrounding area, destroying buildings in its way.

A report by German-based TÜV SÜD a day after the incident said that “based on our current state of knowledge, no damages were found” during their inspection of the dam. The report also showed that the dam held up to the minimum legal requirements for stability.

TÜV SÜD did not respond to a request for comment from Reuters.