East Sussex Fire and Rescue Service (ESFRS) said crews were called to the scene in George Street just after 7.15pm.
A spokesperson said the fire started in a disused three-storey commercial property.
The ESFRS spokesperson said: “We were called at 7.17pm today to attend George Street. We have asked for more resources and informed the police and Secamb. We are treating the incident as persons reported. The fire is in a three-storey former commercial property.
"They have asked for 10 fire appliances and the aerial ladder platform to attend.
"Neighbouring properties are being evacuated and we have asked police to attend to assist with road closures and put cordons in place for public safety. Four main jets are in use now.”
ESFRS said Sussex Police has closed off the road.
The public are being urged to avoid Hastings seafront this evening, ESFRS said in a tweet this evening.
We will have more on this breaking story as we get it.
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The scene of the fire. Picture by Lord Brett McLean Photo: Lord Brett McLean
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Firefighters at the scene. Picture by Abby White Photo: Abby White
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Firefighters at the scene. Picture by Abby White Photo: Abby White
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Firefighters at the scene. Picture by Abby White Photo: Abby White