Parts of a British prison have caught fire after inmates went on a riot there.

At one point, plumes of smoke could be seen coming from the Ashwell prison near Oakham in Leicestershire, 100 miles north of London.

Fire engines, an ambulance and a helicopter are at the scene, and the perimeter has been secured. No casualties were immediately reported.

Several vans filled with prisoners were removed from the scene Saturday as special police squads tried to retake control of the facility.

The riot began early in the day, and Britain's Ministry of Justice said hours later that police were still in a standoff with the rioters.

It was not known how many inmates were involved, but the prison holds about 600.