Brazilian mining company Vale, whose dam collapsed killing at least 150 people, was aware of emergency warning sensor issues at the site two days prior to the disaster, local media have reported.

The iron ore dam, located in the Brumadinho municipality of Brazil’s southeastern Minas Gerais state, collapsed on January 25, triggering heavy mudflows. According to various local media reports, emergency warning sensors at the site failed to go off.

Moreover, media have reported that inspectors pointed to drainage infrastructure problems at the dam and monitoring system issues back in September. 

The Globo news outlet reported on Wednesday, citing e-mail exchanges between Vale’s engineers and employees of two other companies, that the sensor issues had been detected two days prior to the dam collapse.

The company has reportedly shared the e-mails and other documents with the Brazilian police and prosecutors.

The bodies of 134 victims of the dam collapse have been identified, while 183 people are feared missing.