Smoke from one of the fires can be seen from downtown Halifax. (Submitted by Colin Knott)

About 4,000 people have been forced to leave their homes because of an out-of-control fire in a heavily wooded area east of Halifax, officials said Saturday.

Another 2,500 people who live in the Carter Roman subdivision, Beach Breeze Estates and Haylings Acres areas near Porters Lake have been told they will get one hour's notice before they must leave their homes.

RCMP and fire officials on Saturday afternoon said residents in the area should "strongly consider leaving" before a mandatory evacuation notice is issued. But as of Saturday evening, an advisory from the region said nothing had changed.

"The fire is still out of control," Roy Hollett, deputy chief of the Halifax Regional Fire Department, said around 6 p.m. AT.

This photo was taken on Highway 107 around 4:00 p.m. AT on Friday. (Submitted by Bruce Roberts)

Smoke from the fire — estimated to cover 21 square kilometres — was visible for 20 kilometres.

Two homes have been destroyed and three others damaged by the fire, but 12 in the same area were saved by firefighters, even as flames licked at their decks.

No one has been hurt in the fire that has been raging for 24 hours. It is being fanned by strong winds, which are expected to drop overnight. But there is no prospect of rain until late Tuesday or Wednesday.

About 200 people have registered at emergency shelters in nearby Cole Harbour since the fire began Friday.

Hollett said thick smoke has made it impossible to assess all of the possible damage to homes and cottages in the scenic coastal area.

The fire area around Porters Lake. (CBC)

Water bombers from New Brunswick and Newfoundland and Labrador, and helicopters, are aiding about 100 firefighters. The planes are working to control the fire in inaccessible areas, while the crews are concentrating on protecting homes, Hollett said.

The air over part of Halifax was thick with smoke on Saturday. People in the region have been warned to stay inside and keep doors and windows closed.

There are traffic difficulties in the Porters Lake area because exits 17, 18 and 19 from Highway 107 are closed.

Travellers are advised to take the Meaghers Grant route to get from the Eastern Shore to Halifax.

A second fire in the Tantallon district west of Halifax forced the evacuation of a dozen homes. It was still out of control early Saturday evening.

With files from the Canadian Press