Six casualties were treated for chemical inhalation after an incident in the town centre on Sunday afternoon (May 13).
Emergency services were called to a block of flats in Seaside Road following reports of a strong chemical smell and toxic fumes issuing from the building just before 3.30pm.
Police cordoned off the area and firefighters found six casualties suffering from the effects of chemical inhalation.
They were passed into the care of SECAmb.
The cause of the fumes was said to be a drain cleaner.
None of those affected had to be taken to hospital, police confirmed.
A Sussex Police spokesperson said, “The alarm was raised shortly before 3.30pm and led to a 200-metre exclusion zone being created and closure of nearby roads while the incident was dealt with by emergency services.
“The cause is believed to have been a chemical reaction resulting from use of a household cleaning agent.
“There were no suspicious circumstances.”