Explosion in Castlecliff, Whanganui being investigated

Fire investigators are looking into the cause of an explosion at a commercial property in Whanganui this morning.

Fire and Emergency New Zealand crews were called to the property in the Mill Rd/Manuka St area of Castlecliff around 5.30am on Wednesday.

The explosion happened around 5.30am, with locals taking photos of the glow it caused. Photo / Tristian Campbell

Residents took to social media to talk about the explosion and the orange glow that lit up the sky. Some reported seeing flames and billowing smoke, and hearing bangs and neighbourhood dogs barking.

Alison Palmer said she was driving along No 2 Line into town when she saw the sky light up in the distance.

Unsure what it was, she pulled over and started recording a video.

"I thought of all sorts of things it could have been."The first thing that came to mind was another eruption in Tonga, but she realised it was a bit too close for that, she said.

A Fire and Emergency New Zealand spokesperson said investigators would spend the morning at the scene to determine the cause.

Early indications were that the cause was suspicious. It was not yet clear what had caused the explosion, the spokesperson said.

Police said they attended the scene with fire investigators and inquiries into determining what happened were ongoing.