A stretch of State Highway 1 between Gore and Balclutha is closed after a serious two-vehicle crash on the Waipahi Highway on Friday morning, with one person flown out to Dunedin Hospital, where their condition was described as serious.

Police said they were alerted to the collision at about 10.55am. The crash site is roughly seven kilometres northwest of Clinton, in the Clutha district, close to where Springbank Road meets the highway on the Wairuna side of the town.

Injuries were reported, police said, without giving a number. Hato Hone St John told the NZ Herald that one patient was in a serious condition and had been taken to Dunedin Hospital.

Fire and Emergency New Zealand was called shortly before 11am and sent three crews, drawn from the Clinton, Gore and Tapanui brigades, according to the Herald.

The NZ Transport Agency said at 11.45am that the closure ran from the Wairuna Siding Road turn-off to the Clydevale Road junction, and that emergency services and contractors were at the scene. It asked drivers to stay away from the area or put off their trips where they could, and said it would issue further updates as the situation changed.

Police have directed traffic between Southland and South Otago onto State Highway 93, the inland route linking Clinton with Mataura via Waipahi and Clydevale, while the section of SH1 between Clinton and Wairuna remains closed.

The Waipahi Highway, also signposted as the Presidential Highway because of the names of the two towns it links, is the main road for Southlanders heading to Balclutha and Dunedin. It carries freight from the Gore area as well as traffic from Invercargill bound for the Otago coast.

It is the second serious crash on SH1 in Otago in two days. On Thursday afternoon police and fire crews attended a collision at Waihola, south of Dunedin, which closed the highway for a time before it reopened with restrictions in the early evening, according to NZTA updates published through Scoop.

Southland and Otago roads have had a grim week. One person died in a single-vehicle crash on SH6 between Lumsden and Dipton on Tuesday, and another person was killed in a crash in the Kawarau Gorge the same night. Police have not released the names of either victim.

Police have not said whether the Serious Crash Unit has been called to Friday's crash, and no further details about the vehicles or the people involved had been released by early afternoon.

Drivers can check the status of the highway at journeys.nzta.govt.nz/traffic or by phoning 0800 44 44 49. Anyone who witnessed the crash and has not yet spoken to police can call 105.

Update, 6 November: police have confirmed one person died at the scene. Read the latest story.