The bomb squad have been called to Crawley after a suspicious package was found in the town centre.
Police said the package was discovered in a bin in Memorial Gardens at around 6.20pm and the area was immediately evacuated.
A 100m cordon has been put in place around Memorial Gardens and Queens Way while police and Explosive Ordnance Disposal investigate the item.
College Road and Southgate Avenue - between the roundabout at the police station and Debenhams - have also been closed.
Superintendent James Collis said: “We have a 100m cordon around Memorial Gardens and are at this stage are asking people to avoid the area while we investigate.
“We apologies for any inconvenience caused to those who have been evacuated but we are working as quickly as possible to make sure the area is safe.