Police and emergency services have responded to an incident in Eastbourne town centre last night.
Divisional and armed response officers were called to Bourne Street following a report of an assault involving a substance, shortly before 10pm.
Officers remain at the scene while a search of the area is conducted.
Police are appealing to locate a suspect who is described as a white man, aged about 35, 5’7”, of large build and with dark wavy hair who was seen wearing a white T-shirt with writing on the front, and denim jeans.
The incident took place near the junction with Tideswell Road and a man has been taken to hospital with injuries.
Police believe this was an isolated incident, and officers remain at the scene to provide reassurance to the public in the area.
Witnesses or anyone with information is asked to report it to Sussex Police online or call 101 and quote serial 1457 of 18/03.