At least two people died and two more were injured when a bridge under construction collapsed in the Netherlands on Wednesday, Dutch officials said.

"An industrial accident occurred while building a bridge," the regional safety authority wrote on X, formerly Twitter.

"Unfortunately, this resulted in two fatalities. Two people are injured."

Earlier, the authority had said that part of the bridge, under construction in Lochem, in the east of the country, had collapsed.

They had initially given a toll of four injured, three of them seriously. It is not clear whether the two dead were part of that original toll.

A reporter at the scene, from local newspaper De Stentor, said workmen had been hoisting bridge arches when the accident occurred.

"Suddenly there was a huge bang," the reporter said.

"The entire arch started to swing. Then the whole thing fell down. We saw two construction workers fall down."

According to the Dutch labour inspectorate, cited by local news agency ANP, parts of the bridge fell on at least two people.

Images on Dutch media showed rescue helicopters buzzing overhead and emergency vehicles arriving at the scene.

The regional safety authority said there was no indication what had caused the accident and that a probe was underway.

Max Schurink, project manager of the Gelderland province where the building site is located, said he was "enormously shocked", having seen the accident with his own eyes.

"I am seriously concerned for the colleagues who are on site," Schurink told De Stentor. 

Around 40 co-workers who saw the accident are being offered psychological support.

Schurink said conditions around the site were in order.

But he added: "Let's not speculate about the cause.

"Concern now goes out to the employees affected by this accident. It's dramatic enough."