The man on the roof of an immigration centre in Lincolnshire is a Chinese national. Staff at Morton Hall near Lincoln said he took to the top of the 30 foot high building at 1130 BST.
Trained staff are on the roof trying to negotiate with the man who is not said to be making demands. Emergency services were on scene, although several fire engines have now left.
Lincolnshire police were called to a similar incident yesterday when a different detainee also got onto the roof but that was quickly resolved.
More top news
The motorway service station, where a D-Day veteran lost four medals, is offering a reward for them to be returned safely.
The funeral of two schoolboy brothers found dead by police after a domestic disturbance is being held today.
96-year-old Alfred Barlow lost four medals at the Norton Canes services on the M6 Toll.