EDWARDSVILLE, Ill. — Congressional Democrats are accusing Amazon of obstructing their investigation into the company’s labor practices during severe weather events.

Amazon’s policies have been under scrutiny since the deadly collapse of a company warehouse last year in Edwardsville, Illinois.

Regulators found Amazon’s Edwardsville facility met minimal federal safety requirements for storm sheltering but said it had other safety risks.

The House Committee on Oversight and Reform is also investigating the incident. A letter to Amazon’s CEO signed by the committee’s chairwoman said the Seattle-based company has not handed over key documents.

An Amazon spokesperson said the company was surprised to receive the letter. The spokesperson said Amazon has handed over relevant documents and will produce more.