Police are still looking for more witnesses to the suspicious grass fire at Oxley Hill on Monday night, the second in the city in under 12 hours.
ACT Policing superintendent Brett Kidner issued a stern warning to Canberrans following the fire, saying it could potentially have threatened property.
“We’re very lucky that this did not result in injury or damage to any property. During these hot and dry conditions, the community should be aware that even the smallest of sparks can spread quickly and have devastating results.”
The alarm was first raised about 9.15pm and officers spoke with several witnesses who heard a loud explosive noise prior the fire.
ACT Fire and Rescue said they had received more than 240 emergency calls about the fire.
ACT Fire & Rescue units had the blaze out by about 11pm, when the scene was handed over to ACT Policing to investigate the cause.
Anyone with any information about the fire who has not spoken to police is urged to call ACT Policing Operations on 131 444 or Crime Stoppers on 1800 333 000.
Police said all calls to Crime Stoppers will remain anonymous.
The fire began near Newman-Morris Circuit and Schonell Circuit in Oxley and the ACT ambulance service advised residents with breathing conditions to stay indoors.
There was no threat to any properties and the bushfire alert and warning level has been set at advice.
The Oxley fire started after a separate 50-hectare blaze on Monday afternoon near the ACT-NSW border, which authorities believe may have been deliberately lit.
NSW and ACT Rural Fire Service crews responded quickly to the initial fire near Wallaroo, north of Canberra.
The fire began on the ACT side of the border at 5.42pm and about 20 firefighters and five tankers attended the scene. It then spread to the NSW side where it burnt out 48 hectares, but was brought under control by 7pm.
Fire crews were expected to remain at the scene of both fires for several hours on Monday night to continue mopping up.
ACT emergency services also responded to a call about a grass fire in Gilmore at 8.30pm, but when they arrived they were unable to locate any evidence.
The cause of the Wallaroo fire has not been determined, but authorities believe it may have been deliberately lit.