Fire crews, police officers and paramedics were called to a home in Dorset Place just before 10.30am.
"One fire crew remains at the scene.
"Sussex Police and SECAmb (South East Coast Ambulance Service) are also in attendance."
Pictures from the scene show a large number of emergency services responding to the incident.
The road has been closed whilst the incident is ongoing.
This is a breaking news story. Updates will follow as and when we get them.