About a dozen people are missing in St Helier and there are two “walking wounded” being treated at the hospital, officials say.

Chief of Police Robin Smith said he expected the search and rescue effort to take “a number of days”.

Robin Smith, chief officer at States of Jersey Police, said the force received reports of a “large explosion” at roughly 4am on Saturday at a block of flats in Pier Road, St Helier.

Mr Smith said: “There are of course a number of other people that are unaccounted for and therefore a search and rescue operation has commenced.”

He said Jersey Fire and Rescue Service were liaising with Hampshire Fire and Rescue to help with the search.

Mr Smith added between 20 and 30 people evacuated from the area had been taken to St Helier Town Hall.

The force 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.”

The force said the fire has been extinguished, but emergency services are still “carrying out significant work” at the scene, which is cordoned off, and people have been asked to avoid the area.