Police raided two locations on Thursday as part of their probe into a fire that broke out in a noise-barrier tunnel along an expressway in Gwacheon, Gyeonggi Province a week earlier that killed five people.

The Gyeonggi Nambu Provincial Police Agency said on Friday that it conducted a five-hour raid of the Gyeonggi office of the Second Seoul-Incheon Linking Highway Company and the Seoul office of its subcontractor.

Investigators seized various manuals and electric data related to fire safety facilities.

A police official said the agency will analyze the confiscated material to determine whether adequate measures were put in place to respond to the fire.

The raid comes after police booked two employees of the highway operator on charges of causing death by negligence for failing to take appropriate follow-up measures after the fire started.