Darwin residents have been battered by Tropical Cyclone Marcus and are being urged to stay at home and out of danger until emergency services secure the city.
Winds up to 130km/h brought down trees and power lines on Saturday as the cyclone swept through the city, with the storm system now heading southwest.
Many power lines are down with some still live, said NT Police and Fire and Emergency Services in a joint statement.
Trees have fallen throughout the Greater Darwin region and while the major arterials are accessible, some are not yet fully cleared.
Residents are set for a massive clean up following the destruction of Cyclone Marcus. Source: AAP
"It's only been several hours since the cyclone passed," Regional Controller Warren Jackson said in a statement.
"Many hazards are present and public safety is our priority."
"While assessments of damage are undertaken, it is safest for community members to stay home."
NT Emergency Services crews have begun to respond to more than 400 calls for help in the aftermath of the cyclone and have started clearing debris around Royal Darwin Hospital and the airport as a priority.
Many residents will be commencing a massive clean-up operation on Sunday.
"Don't take unnecessary risks - only travel if it is absolutely required," Regional Controller Jackson said.
The eye of the category one storm moved off the coast near Daly River Mouth late afternoon on Saturday.
Marcus is now headed as a category two storm towards the Timor Sea and is expected to hit Western Australia's Kimberley Coast on Sunday, bringing wind gusts of up to 120km/h.
It will then continue moving westwards, into the Indian Ocean.
Saturday's storm also affected Darwin's drinking supply.
Residents have been told to boil drinking water as a precaution until further notice.
One Darwin resident said "Marcus sure packed a punch" and showed a photo of a huge fallen tree that had crushed her parents' home in the city's north.
Earlier in the day, water police were called out to rescue two people from two boats that collided after one of them slipped its moorings in Sangove Creek as the storm struck.
Officers rescued an elderly couple from one of the boats and two people from the other vessel, which was taking on water, however a third person refused to leave.
The latest advice from the Bureau of Meteorology says a warning is in place for Dundee Beach to Mitchell Plateau and a Watch for Mitchell Plateau to Cockatoo Island.
Flights in and out of Darwin were cancelled on Saturday but flights will resume after midnight. The first flight is due at 4.15am Sunday and all of Sunday's flights will operate as scheduled, according to the airport.
