A man was arrested on Sunday after shots were reportedly fired inside Canberra airport’s main terminal, Australian police said.

“The Canberra Airport terminal was evacuated as a precaution and the situation at the airport is contained,” the police said in a statement. “There have been no reported injuries.”

Canberra Airport has resumed normal operations following a shooting in the main terminal which shut down flights for hours.

Canberra Airport confirmed flights resumed from 5pm on Sunday after hundreds of terrified travellers were forced to flee as a gunman opened fire inside the airport.

A man was arrested over the incident and police say he was acting alone. No injuries were reported. 

'The airport has resumed normal operations. Please check your travel plans directly with your airline if you are travelling today,' the airport announced in a tweet. 

Although planes have now been permitted to take off, an active crime scene is still being combed through by investigators and passengers are still struggling to check-in for their flights.

Social media posts show long queues at the airport as airlines hurry clear the backlog of cancelled and delayed flights.

The sound of gunshots was initially reported from the security checkpoint inside main terminal building at about 1.30pm on Sunday with terrified passengers told to 'get down' and 'run'.

The airport was quickly evacuated with confused travellers forced to wait outside in the cold for several hours as police checked the building.

Passengers onboard inbound flights were told to wait inside the planes until about 3.30pm. 

One passenger stranded on a plane tweeted: 'Stuck on a plane on the tarmac while there is apparently a shooter in the Canberra airport....what the f***is going on???'. 

Detective acting superintendent David Craft confirmed one man was arrested and a firearm was recovered from the scene. 

Mr Craft said the man spent about five minutes sitting in the departures area on level two before allegedly firing five rounds into airport windows.

He said police have 'no idea' what his motivation was and believe he acted alone.

Police said the man did not target passengers or staff members and had not yet passed through the security checkpoint.

'CCTV has been reviewed and at this time the person in custody is believed to be the only person responsible for this incident,' police said in a statement earlier today.

'The Canberra Airport terminal was evacuated as a precaution and the situation at the airport is contained.

'ACT Policing requires members of the public to not attend the airport at this time.

'There have been no reported injuries.

'ACT Policing have taken carriage of the incident and a further update will be provided later today.'

A video captured by a witness inside the terminal shows the suspect being pinned to the ground by potentially-armed police. 

The video then shows another officer rushing over to help and the man being led away in handcuffs.