Fire investigators will soon be able to determine the cause of a fire that destroyed CTV Ottawa's newsroom over the weekend.

A transmission tower on top of the building is now secure and an air conditioning unit on the roof has been removed.

Fire investigators were prevented from entering the building yesterday, out of fears the transmission tower could topple. They are now waiting to get clearance to enter the building over concerns of asbestos.

It will likely take days for investigators to determine the exact cause of the fire.

Damage to the building is estimated to be at least $2.5 million. The inferno destroyed the CTV Ottawa newsroom, ripping through the second floor and causing computers to melt into puddles.

Only a security guard was on duty at the time of the fire. Nobody was injured in the blaze.

However, it is feared decades of the television station's video history was lost.