Construction workers had to jump to safety after a huge crane overturned on a building site in Dublin.

The incident is being investigated by Gardaí and the Health and Safety Authority.

The five-axle, all terrain crane is capable of lifting loads of 200 tonnes and comes with a seven section arm that can extend to 68 metres high.

The crane was located on a large commercial building site in Blanchardstown when the incident happened. The cause of the accident is unknown and several construction workers had a lucky escape.

In video footage of the incident, the rear of the crane is seen to lean backwards and then tilt forwards, crushing the forward driving cab.

The crane then tips sideways and overturns in a heap. A worker is seen to jump from from the operator cabin in the middle of the crane as it hits the ground. A construction worker on the ground is also seen to run away from the crane and dive for cover in a trench.

At least five other construction workers can be seen in the vicinity of the crane.

Two investigations are now underway into the incident and it’s not yet clear if there were any injured.

"The HSA are aware of this incident and are making the relevant enquiries at this time,” the Health and Safety Authority said.

“Gardaí are conducting enquiries following reports of a workplace accident in Dublin 15 this morning,” a Garda spokesperson said.

The accident happened on the campus of the Astra Zeneca pharmaceutical giant.

The company says nobody was injured and building site remains closed.

"An incident occurred yesterday (30th Nov) in the API construction area of the AstraZeneca/Alexion College Park facility involving a crane. All site personnel have been reported safe and there were no injuries.

"The construction area was declared closed immediately following the incident and will remain closed until further notice. We are working with the relevant authorities and an investigation is currently underway, with all health and safety protocols being followed," a spokesperson said.

Six weeks ago, the operator of a smaller crane had a lucky escape when the machine he was working with overturned on a site in Waterford.

The crawler crane, which runs on tracks, was working on the North Quays development in Waterford City.