A pedestrian is critically injured after they were reportedly struck by a sightseeing bus in Gillies Ave, Epsom on Wednesday morning.

St John said they transported a person with critical injuries to hospital after the crash near the intersection of Gillies and Alpers Ave. They were called to the scene at 9.19am, a St John spokeswoman said.

Newshub is reporting a tour bus was involved in the incident. The Herald has sought comment from the tour company.

Motorists are being warned to delay their journey or avoid Gillies Ave completely after the crash between Alpers Ave and Owens Rd. Gillies Ave forms part of a major route to the airport.

Auckland Transport said southbound lanes were now closed between SH1 interchange and Owens Rd.

The traffic agency said northbound lanes remain open however significant congestion is occurring in the area.

Police said a pedestrian was seriously hurt in the crash and a section of both roads will be closed while the scene is examined.

“Motorists are advised to expect delays and to choose an alternate route where available. The Serious Crash Unit is in attendance,” police said.