PHOTOS: Hampshire rescue services called to Didcot Power Station disaster

The Eastleigh-based urban search team from Hampshire Fire and Rescue Services headquarters are carrying out a search at Didcot Power Station.

The group, which is the same team that went to Nepal after a horrific earthquake last year, includes two specially trained search and rescue dogs, two handlers and a rescue advisor as well as two vehicles.

It is "highly unlikely" three people missing after part of a power station collapsed are alive, emergency crews have said.

One person died and five are in hospital after a concrete and steel building at the derelict Didcot A site in south Oxfordshire came down at around 4pm on Tuesday while it was being prepared for demolition.

Dave Etheridge, Oxfordshire Fire and Rescue Service Chief Fire Officer, said: "We have just spoken to the families who are obviously distraught.

"We have explained to them we have not picked up any signs of life but we are doing everything we can to locate their loved ones.

"It is highly unlikely they are alive."

He said the operation "may take several days, possibly several weeks", while Thames Valley Police Assistant Chief Constable Scott Chilton described those in hospital as "seriously injured, but not critical".

A 100m cordon has been placed around the scene as the rescue operation, which has involved specialist officers from around the country as well as sniffer dogs, continues.

Pictures from the scene showed a significant chunk of a building in the defunct Didcot A site has collapsed, with a large amount of debris on the ground.

A Health and Safety Executive (HSE) spokeswoman said two investigators were called to the scene on Tuesday evening and were continuing to work with police.

Mr Chilton said: "This is a tragic event and we are doing all we can to support those families.

"The priority at this time is the recovery of the persons missing."

mfl Describing the rescue operation to find the missing trio, Mr Etheridge said: "We have tried their construction site radios and have had no response. We see this as significant.

"The rescue teams have been working and continue to work through the debris. The rescue teams are working under very difficult circumstances with a structure that is unsafe, with unsafe and unstable material from parts of the collapsed building.

PICTURED: Members of the Hampshire rescue team in Nepal

"We are currently using sniffer dogs, listening devices, drones, and are looking at the possibility of possibly deploying remote control probes into the structure to access the dangerous parts of the site. This will enable us to cover areas that are too risky for rescue teams to be deployed to.

"Progress has been slow, but we are making progress working through the debris. This exercise is going to be prolonged and very difficult."

He said he had given a personal assurance to the families of the missing that rescue teams will do "everything they can" to recover the loved ones.

The building was due to be demolished when it collapsed, emergency services said, while the Health and Safety Executive (HSE) confirmed it was on site investigating.

David Cameron updated MPs on the "dreadful accident" and subsequent rescue operation - which involved a team of more than 100 people - at the start of Prime Minister's Questions.

He said: "I know the whole House will join me in sending our condolences to the family and friends of the victim and our best wishes to all those still missing or injured.

"I also want to pay tribute to the quick and incredibly brave actions of our emergency services who dealt with the incident with typical professionalism."

Didcot A opened in 1970 as a coal-fired power station and was later converted so it could also generate power from natural gas.

It ceased generation in March 2013 and hundreds gathered to watch when three of its enormous cooling towers were blown up in July 2014 after dominating the town's skyline for more than four decades.

The incident comes 16 months after a major fire struck a cooling tower at Didcot B in October 2014.

The blaze affected 50% of the station output - supplying a million homes.

Barry Wells, who lives in Didcot, said he worked at the power station from 1970 to 1972 as a steel fabricator.

He told the Press Association: "It is a major disaster, this shouldn't have happened."

The 61-year-old described the partially collapsed building, which is also known as the turbine holder, as "huge" and "cavernous" inside.

He said: "There were levels but the main building was the turbine holder that housed four massive great generators, turbines, that ran the power station and produced electricity.

"And there were huge great, giant cranes inside too - it is an immense place."

He said the roof of the building is made of small glass window panes to add light to the building.

"That will have made one hell of a mess when that came down with it," he added.