A fire that broke out at an unoccupied apartment block in O'Connor on Wednesday morning is being treated as "suspicious" by police, who are investigating the incident and urging anyone with information to come forward
The building was vacant and no one was injured but the apartments sustained significant damage, police said.
The building was not connected to power.
Emergency services were called out to the fire on Berrigan Crescent at around 1.30am on Wednesday morning.
An ESA spokesperson said a large number of crews spent several hours battling the blaze before they could bring it under control just after 4am.
ACT Fire & Rescue northside commander Brett Slater said crews responded with four pumpers, and aerial and support apparatus.
"On arrival the crews discovered a fire on the top floor," he said.
"The fire got into the ceiling space and took considerable amount of resources to extinguish it."
A large number of personnel and equipment are expected to remain on the scene through the morning and people are advised to avoid the area.
The cause is unknown but it will be examined by fire investigators and police.
It is expected to have significant traffic impacts on Berrigan Crescent throughout Wednesday morning while emergency operations are underway.
Anyone with information about this incident is urged to contact Crime Stoppers on 1800 333 000 or via www.crimestoppers.com.au, quoting reference number 7648897.
