POLICE officers have been carrying out a search in North Harbour.
A van and four police cars have been parked in Western Road since 8pm and have been searching the area.
Police dogs were let off their leads.
Workers at Lakeside North Harbour were being escorted to their cars at about 11pm.
A spokeswoman for Hampshire police said there was no danger to the public.
She said details of the incident could not be disclosed as it was not in the public interest.