ITV's London HQ was hit by a security alert last night after the latest episode of Ant and Dec's Saturday Night Takeaway.
Police were called to the building, with pictures published by the newspapers showing officers inside talking to staff.
The drama unfolded at around 11.00pm, less than three hours after Takeway's live broadcast ended at 8.30pm.
ITV described the incident - which occurred after audience members had gone home - as a "prank".
A statement from ITV read: "A youth who attempted to gain access to the London Television Centre, as a prank, at 11pm last night was quickly apprehended by our security team when he triggered an alarm as he climbed an external wall.
"He did not gain access to our studios, which were not in operation at the time."
Ant and Dec joined them for a performance of some of their biggest hits, including 'Prey' and 'Never Forget'.
Meanwhile, a stunt challenged viewers to transport their own sofas to mystery locations for the Sofawatch segment.
Takeaway's series finale on April 8th will see the boys host the show live from Walt Disney World in Florida.