Robin Smith, the chief officer of the States of Jersey Police, told a press conference that "around a dozen" residents are missing following a blast in St Helier on the south of the island.

Speaking at a press conference on Saturday morning, Mr Smith said the fire service had been called to the area the night before after residents reported smelling gas.

Photographs shared online show smoke billowing above the blaze in St Helier in the early hours of Saturday.

The aftermath of an explosion and fire at a block of flats in St Helier, Jersey. (Pic: @just_daniel1411)

Mr Smith described the scene as "devastating" and warned there could be more fatalities.

He told journalists: "We have a three-storey building that has completely collapsed - described from a demolition point of view as a pancake that has dropped almost straight down. There is also damage to a nearby building as well, another block of flats that the fire service needs to make safe. It is a pretty devastating scene, I regret to say."

When asked how many people were thought to be missing, he said: "Given the destruction of the building it is hard to properly assess the numbers. We are looking in the region of around a dozen, currently. That number could fluctuate, but that's the number we're operating to."

When asked whether there are likely to be more deaths, Mr Smith said: "I wouldn't want to speculate on those sorts of things... but there has to be a recognition that we could have more fatalities."

The police chief said the building is managed by Andium Homes, and their chief executive is "working very hard to look after" those affected.

Mr Smith said police would investigate "whether or not there was a safety issue" regarding gas supplies.

Andium Homes, a state-owned but independent company which rents out thousands of properties on the island, said on Twitter: "We are working with the emergency services responding to the incident at Haut du Mont this morning.

"Our focus at the moment is on supporting our residents on that estate. Our thoughts are with them and their families at this time."

Emergency services have told Jersey residents to avoid using A&E apart from in an emergency, and police have advised people to avoid the area of the blast, which has been cordoned off.

Police said while the fire has been extinguished, emergency services are still "carrying out significant work" at the scene.

The force also said in a statement: "Following the explosion this morning at Haut du Mont, Pier Road, a number of residents are still missing.

"Emergency services are working at the scene and have commenced a surface search of the site. Relatives are being contacted by family liaison officers."

Jersey's chief minister Kristina Moore said the area would be under investigation for "some days" as she expressed condolences to families affected.

Speaking alongside Mr Smith at the conference, she said: "It's a huge shock to everyone this morning, but in the first instance our condolences go to the families who are affected and we're all thinking and praying for those who are worried about their loved ones. We all share in their concern."

Ms Moore said she would keep islanders updated as investigations continue.

Jersey explosion: One dead, around 12 missing after explosion on block at flats