Three people have died and one person is in a critical condition following a two-vehicle crash at the Kopu Bridge, Coromandel, this evening

The bridge south of Thames is closed in both directions following the accident.

Police said there were two people in each vehicle.

Emergency services were called to the south side of the bridge at 8.30pm.

Multiple police units, ambulance, fire trucks and a rescue helicopter are responding to the accident. The Serious Crash Unit is also attending.

Diversions are in place at the Kopu roundabout (intersection of SH25 and SH26) and at SH25 and Hauraki Road. These are likely to remain in place until at least midnight.

A Fire and Emergency spokesperson confirmed four people were trapped.

A local resident told the Herald a rescue chopper landed at the scene about 9.20pm.

Motorists are asked to avoid the area with diversions in place.

Kopu Mobil station worker Neil said he didn't see or hear the crash, but there'd been a flurry of police activity.

"Three, four cop cars came flying past, and then probably three fire trucks.

"They were in a hurry, it seemed very dramatic, so something bad's happened."

The bridge forms part of State Highway 25, connecting Thames to the Hauraki district.

He said the station was full at the time of the crash.

"It's been really busy here... and with the school holidays, there's a lot of people on the road."

In a statement, NZTA said: "Due to a crash on the Western side of the Thames Bridge, the road is closed. Emergency services are on site. Please delay your journey or use an alternative route."

The Kopu Bridge was replaced with two-lane bridge in 2011. It spans the Waihou River, near its emergence into the Firth of Thames and is 587m long.

A total of 124 people have died on the country's roads so far this year.

Police were called at 6.30am this morning to another two-car crash on SH2 just north of Dannevirke, where a motorist died.