The National Police Agency's special investigation headquarters raided 55 government offices on Tuesday as part of their probe into the Itaewon crowd crush.

Investigators converged at the offices of Police Commissioner General Yoon Hee-keun and Seoul Metropolitan Police Agency chief Kim Kwang-ho, among other locations.

Police are also searching for related materials at seven locations affiliated with the fire service, including the Seoul Metropolitan Fire and Disasters Headquarters and the Yongsan Fire Station.

With Tuesday’s raids, police are seeking to secure cell phones of key suspects and witnesses as well as documents, surveillance footage and computer data related to the Halloween festivities in Itaewon.

The raids come six days after the police combed through eight places, including the Seoul Metropolitan Police Agency, the Yongsan Police Station and the Yongsan District Office.