A theatre and a concert hall in the centre of Birmingham were evacuated earlier following reports of an explosion.
People were lead away from the Rep Theatre and Symphony Hall on Broad Street following a loud bang at about 20:00 GMT.
West Midlands Police said there had been a “technical fault” in the theatre’s basement.
There are no reports of any injuries but roads in the area remain closed.
In a tweet West Midlands Police said: “This will have been a very frightening experience for everyone”.
All businesses on Birmingham’s Broad Street are open as usual.
Police said theatre-goers are being looked after at another venue.