An explosion and fire in an apartment building on the Channel Island of Jersey has killed at least three people and left up to a dozen missing, police said on Saturday (Sunday NZ time).

Robin Smith, the chief officer of the States of Jersey Police, said during a news conference that “around a dozen” residents were missing after the blast in the town of St Helier.

Jersey, the largest of the Channel Islands, is a self-governing dependency of the United Kingdom located off the coast of northern France in the English Channel.

Smith said a three-story building had “completely collapsed” and there was also damage to a nearby building.

He described the scene as “devastating” and warned there could be more fatalities.

Smith said the fire service had been called to the area the night before, after residents reported smelling gas.

He said police would investigate “whether or not there was a safety issue” with natural gas lines.

Police said in a statement that while the fire was extinguished, emergency service agencies were carrying out significant work” at the scene.

Smoke and flames can be seen after an explosion in an apartment building in Jersey that has killed at least three people and left about a dozen missing. Photo / Supplied

Authorities advised Jersey residents to only seek emergency hospital care in the event of an actual medical emergency and to avoid the area of the blast, which was cordoned off.

The BBC reported people across the island heard a loud bang and saw a large plume of smoke. It reported officials saying the search of the scene could take days, even weeks. - AP