Update 5.50pm: A huge fire which broke out in a block of toilets at Nottingham station in England is being treated as arson.
Around 60 firefighters tackled the blaze which started at 6:30am and spread to the main concourse and the roof.
A joint investigation between British Transport Police (BTP) and Nottinghamshire Fire and Rescue was launched, and BTP said this evening that they are treating the fire as arson.
Firefighters are still at the scene dealing with the fire, which has been brought under control.
Supt Sandra England, who is leading the BTP response, said: "Inquiries have been ongoing today and we now have reason to believe the fire may have been started deliberately.
"Officers are working to identify anyone who may have been involved in the incident, and we are appealing for information from members of the public.
"Fortunately, we have not had any reports of injuries as a result of the fire.
"Cordons remain in place around the area and trains are not running. It is likely the station will remain closed for the rest of the day."
Earlier: Large blaze at UK train station being tackled by 50 firefighters
Fifty firefighters are tackling a large blaze at Nottingham station.
The building was evacuated and no injuries have been reported.
Picture from inside the train station here shows the conditions our firefighters are working in to keep you safe - currently working to stop the spread, please bear with us whilst we work to tackle the fire! #NottinghamTrainStation #HereForYou 🚒🔥 pic.twitter.com/qcwSFn7SyC— Notts Fire (@nottsfire) January 12, 2018
Trains will not be stopping "until further notice", a spokesman for East Midlands Trains said.
Nottinghamshire Fire and Rescue Service tweeted: "There are now 10 fire engines in attendance approximately 50 firefighters fighting the fire at the #NottinghamTrainStation".
Nottinghamshire Police said surrounding roads are closed.
The force tweeted: "Station Street, Carrington Street and Queen's Road have been closed. Transport in the area will be severely disrupted."
A spokeswoman for East Midlands Ambulance Service said it is aware of the incident.
This is a fully developed fire in the main concourse of the station - which has spread to the roof. Crews are currently working to stop the fire from spreading, thank you for your patience whilst we work to keep everyone safe! #NottinghamTrainStation 🔥🚒— Notts Fire (@nottsfire) January 12, 2018
"We have a clinical manager and specialist paramedics at the scene," she said.
Travel disruption information posted on the East Midlands Trains website said: "At present we do not have a firm estimate as to when the station will be able to re-open; however, we expect trains to be disrupted on all routes through Nottingham for the whole of Friday 12th January."