Police have raided Muan International Airport and other locations as part of an investigation into the Jeju Air plane crash that killed 179 people on Sunday. 

The regional police of South Jeolla Province raided the offices at the airport and the Busan Regional Office of Aviation, as well as Jeju Air’s office at Gimpo International Airport in Seoul, starting at 9 a.m. Thursday.

The purpose of the raid is to secure materials to determine whether the ill-fated aircraft was operated in accordance with regulations, whether it was maintained properly, and whether the airport facilities were built and maintained in compliance with relevant laws and regulations.

A police official said the force will thoroughly examine all aspects of the disaster.