The leader of Preston Council has urged Christmas shoppers not to be deterred by the security alert at a shopping centre.
But he has urged people to remain vigilant, after the Fishergate Shopping Centre was locked down for hours.
Police and bomb disposal experts were called in, after the “crude” device went off in the men’s toilets.
Coun Peter Rankin, leader of Preston Council, said: “Clearly, it’s a concern that a small crude device like this has been deliberately placed in the toilets of a Preston shopping centre.
“We are working closely with the police who are investigating the incident.
“The city centre is open and we’d encourage people to go about their normal business, although remain vigilant as ever.
“We would like to thank the police and the emergency services for the professional way they have handled this incident.”
The manager of the Fishergate Shopping Centre, Keith Mitchell, thanked customers for their patience.
He said: “The safety of our customers, colleagues and staff is paramount and centre staff carried out our evacuation procedure calmly and efficiently.
“We would like to thank all our customers for their help, understanding and patience and the emergency services for their professionalism during this incident.
“We are liaising with the police and working with them to get the shopping centre reopened and back to normal as soon as we possibly can.”
Police stood down at about 6pm - nine hours after the centre was evacuated - and said things were “returning to normal”.
In a message on Twitter, police said: “We’ve released the Fishergate Centre back to the management. They’ve decided it will remain closed tonight and re-open as usual tomorrow.”
They added: “Officers will remain in the city centre tonight supported by a large number of specials who have come in from across the force to assist.”