A massive blackout has, in effect, shut down Darwin, leaving the entire city without power.

Schools, public offices and public transport services are all shut as the Northern Territory capital remains without electricity following an outage just before 1.30am.

The Northern Territory government has said that all schools will be closed and has encouraged public servants who do not work at the hospital or in "critical roles" to stay at home until power is restored.

"The NT Public service has mobilised its emergency management protocols to ensure the community's safety," a government statement read.