An explosive device was found in the Fishergate Shopping Centre mens toilets in Preston.
AdvertisementPreston Police said the small device went off and could have caused injury.
The bomb squad remains at the scene in Preston as Butler Street and the shopping centre are closed.
Chief Superintendent James Lee from Lancashire Police said: “We’ve evacuated the centre while bomb disposal retrieve a small incendiary device.
“All I can tell you it was small. I believe it could have caused injury or damage to something if it had not been found.
“It was found in the toilets.
“Investigation is already commencing. We’ve got detectives on the case.”
Police have now released CCTV footage of a man they would like to speak to in connection with the incident.
Replay: Live broadcast from Butler Street and interview with Chief Supt James Lee
The shopping centre is understood to remain closed for the remainder of Thursday as police continue to search the centre.