Fire fighters were called to a fire at a flat, which they believe was started deliberately.
Fire crews were called to the address in Orchard Road, Hove, at about 4am.
The occupants of the flat had already safely left the building.
A spokesman for East Sussex Fire and Rescue Service said: "We were called to a small fire in a flat, which we think may have been deliberate."
Sussex Police are investigating and anyone with any information on the cause of the fire should call 0845 6070999.
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