Police have released footage of a man they believe has information about the bomb found in the Fishergate Shopping Centre.
The shopping centre remains closed as the bomb squad and Preston Police continue to search the building.
A small explosive device was found in a toilet in the centre, and did ‘go off’ according to police.
Shopping centre managers took the decision to evacuate the building shortly after 9am on Thursday.
Butler Street was reopened shortly after 5pm to traffic and pedestrians, as well as the railway station.
Footage released by police shows a man walking in the St Georges Shopping Centre just after 8.30am on Thursday.
Detective Chief Inspector Jill Johnston, of Preston Police, said: “We are keen to speak to the man in this CCTV as we believe he could have information which could assist us.
“We are treating this as a criminal investigation and while the motivation for this incident remains unclear at this stage, we believe this device has been left there deliberately and did have the potential to cause serious injury if it had exploded.
“I would appeal to anyone who recognises this man, or who has any other information which could assist to get in touch with us.”
Update: A 27-year-old man has been arrested on suspicion of arson with intent to endanger life
Replay our live video interview with Chief Superintendent James Lee about the incident
Anyone with information is asked to call police on 101 quoting log 293 of 17/12