An emergency warning is no longer in place as authorities continue to try to bring the fire under control.

People in the area are being advised to remain alert.

Firefighting crews from ACT and NSW are battling the bush and grass fire. Two large air tankers are also at the scene.

NSW Rural Fire Service's Fred Nichols said 22 ACT Rural Fire Service units were on the scene supported by six bulk water vehicles, and eight aircraft. 

"They have plenty of personnel on that," he said. "There will be a lot of mopping up with 400 odd hectares there but there has been no property loss reported so far." 

The road has been closed.

A private contractor trucking water in to help the firefighting efforts on the ground told Fairfax Media he and other contractors had been called in to help deliver water to the firefighting trucks.

He said the Sutton village was looking safer as at about 6.10pm, however the fire was burning aggressively towards Gundaroo.

“A lot of private contractors are bringing water as fast as they can,” he told reporters.

The grassland fire was quickly upgraded to an emergency warning at 4pm, and has been described as burning in a reasonably well populated area.

As at about 6pm, the fire was being brought under control, according to NSW Fire and Rescue.

Emergency services said there is no threat to the ACT at this time. 

The fire is generating large amounts of smoke which are covering north Canberra.

If there is any threat to the ACT from this fire or any other fire that may start appropriate alerts and or warnings will be issued immediately, a spokesman said.

The Fires Near Me website says the out of control fire is more than 300 hectares.