A police incident has been unfolding in Hampden Park since 10pm last night (June 29).
A large police presence is still on scene in Argyll Court, off Faygate Road, as of 9am this morning (June 30).
Fire engines and ambulances are also present.
Sussex Police confirmed officers are dealing with an incident but would give no further details at this time.
One witness said emergency services were responding to a standoff, but this has not been confirmed.
Officers were also seen in riot gear entering a block of flats in the road.
More information when we get it.