Emergency crews have said it is "highly unlikely" three missing people are alive after the disused Didcot A power station in Oxfordshire collapsed.
One person has been confirmed dead and five people have been taken to hospital, two with serious injuries and three with minor injuries, after the power station collapsed at around 4pm on Tuesday.
Sniffer dogs, listening devices, and drones are being used to scour the wreckage, which is up to 30ft high in some places. Around 40 emergency service personnel are on the site, down from 100 overnight.
"We have not picked up any signs of life from the listening devices we deployed at this incident," Oxfordshire fire and rescue service chief Dave Etheridge told a press conference.
"The extent of this incident, the nature of the collapse and the location of the missing people and where they were working means that it is highly unlikely that the missing people are alive."
Etheridge said rescue crews were working under "very difficult" circumstances as the stability of the remaining building was deeply compromised and "could also collapse at any time".
As a result, he said, emergency services were now considering deploying "remote-controlled robots" to access areas of the site deemed too dangerous.
"Progress has been slow, but we are making progress working through the debris," he said. "We anticipate this exercise will be prolonged and very difficult." He warned the investigation may take "several days or several weeks".
He emphasised that his thoughts, and those of the emergency personnel working on the site, were with those families affected.
Thames Valley Police Assistant Chief Constable Scott Chilton, also speaking at the press conference, said the condition of the five individuals hospitalised was "serious but not critical".
Around 50 people have also been treated for dust inhalation after the collapse.
Oxford council area manager Matt Carilie confirmed to BuzzFeed News there had "been one fatality" and that "three persons are currently missing".
Ed Vaizey, Conservative MP for Didcot and Wantage, said this morning he understood that the man killed, as well as those missing, were not from the local area.
The Oxfordshire fire and rescue service has taken command of the site, working alongside other emergency services.
The South Central ambulance service declared the emergency a "major incident”.
A spokesperson for the service told BuzzFeed News the Hazardous Area Response Team (HART), a rapid-response vehicle, six ambulances, and both air ambulances for the region were called to scene on Tuesday. They said three staff members attended.
In addition, five fire engines were at the scene along with support vehicles, including specialist rescue-and-command support units. Urban search-and-rescue Units from Buckinghamshire and Essex were also in attendance, alongside extensive resources from Thames Valley police.
Police told BuzzFeed News that officers were at the scene in Oxfordshire, but declined to release any further details.
In a statement, NPower said the building collapsed while an external contractor worked on it. The company said its thoughts "were with all the families involved in this tragedy".
Images on social media showed the dramatic moment when Didcot A – which was scheduled to be demolished towards the end of February – collapsed.
Coleman Demolition, the firm due to carry out the planned destruction, tweeted that it was aware of the incident.
David Cameron said during Prime Minister's Questions on Wednesday that his thoughts were with the families of those affected. Labour leader Jeremy Corbyn said such incidences highlighted the importance of the emergency services.
Didcot A opened in 1970 but was shut down three years ago.
Part of the station was destroyed in a controlled explosion in July last year, but the core section of the site has remained in service.