Pyongyang is also the seat of all major North Korean security institutions. The largest of them, the Ministry of People's Security, has 130,000 employees working in 12 bureaus. These oversee activities including: police services, security of party officials, classified documents, census, civil registrations, large-scale public construction, traffic control, fire safety, civil defence, public health and customs. Another significant structure based in the city is the State Security Department, whose 30,000 personnel manage intelligence, political prison systems, military industrial security and entry and exit management.