Police say there are currently no further details about the nature of the device, which appears to have gone off causing no real damage and no injuries.
The bomb disposal team are in place to deal with the device.
Lancashire Police were called at around 9.10am today to a report that a device had been found within a bin at Preston's Fishergate Shopping Centre. The shopping centre management decided to evacuate the centre as a precaution.
Police are in attendance at the centre and are asking the public to stay away from the area.
A police spokesman said: “The safety of the public is our top priority and so the Fishergate Centre has been evacuated as a precaution and is currently closed. The rest of Preston town centre remains open for business.
“Our colleagues from the EOD have been called to assist us with our inquiries and to help in the disposal of the device.”
Traffic is very slow at the junction between Mount Street and Butler Street.