Paramedics were called to the crash about 8.40am on Monday, a NSW Ambulance spokesman said.

They assessed two patients, including a child, and transported another two by road to the Canberra Hospital.

The two patients assessed at the scene were understood to be walking around immediately after the crash.

An ACT Health spokesperson said those taken to hospital sustained minor injuries and were in a stable condition.

They said one was discharged by 4.15pm and expected that the others would be released by Monday evening.

Motorists experienced significant delays in both directions in the hours after the crash.

The northbound lanes of the Barton Highway were closed until 10.45am, with traffic diverted down Nanima Road. Heavy vehicles are unable to use this route.

Traffic in the south bound lanes moved via a stop/slow management while police investigate the crash site.

The highway has now reopened in both directions.

The crash was one of two which impeded traffic on the Barton Highway on Monday morning.

A minor two-car collision at the Gungahlin Drive on-ramp of the highway at Kaleen temporarily closed the road. No one was injured.