TORONTO -- Firefighters have put out a smouldering fire at Toronto's landmark CN Tower that broke out in the early morning hours Wednesday.

Toronto fire services tweeted just before 7:15 a.m. that the flames at the CN Tower's main antenna mast had been put out and firefighters were coming down.

Toronto Fire District Chief Stephan Powell said earlier the fire broke out around 4 a.m.

He said crews had turned off power to the antenna, which affected some local TV and radio signals.

The chief said firefighters had to use ladders above the SkyPod observation platform to reach the fire.

Some 30 emergency workers and about eight fire trucks were at the scene.

Neil Jones, chief operating officer for the CN Tower, said there was no threat to public safety or the structure.

He said all cleaning staff were cleared from the building and no injuries have been reported.

He added that the CN Tower will be opening to the public Wednesday once Toronto fire officials give the green light.

The CN Tower is a concrete communications and observation tower in downtown Toronto that is more 550 metres high.

It held the record for the world's tallest free-standing structure until 2007.