Police in Birmingham, England, say a very credible and specific threat prompted them to order 20,000 people to leave their homes and jobs in the city's busy entertainment district Saturday.

A senior regional police official, Chief Constable Paul Scott-Lee, said Sunday that the threat no longer exists, but that earlier intelligence indicated "the people of Birmingham were in danger." Police say the situation in Birmingham was not linked to the terrorist bombings in London, but they declined to disclose any other details.

Birmingham police collected four suspicious packages during their searches, all of which were found to pose no danger to anyone. However, they said discovery of the packages was not the reason for the security alert.

The evacuation order was lifted early Sunday. Police say no one was arrested, and there were no injuries during the overnight security operation.

Birmingham is Britain's second largest city, and is about 175 kilometers northwest of London.

Some information for this report provided by AFP and AP.