A huge blaze spread through six buildings in Al Balad, Jeddah's old town, on Tuesday night, according to Saudi media.
Three of the six buildings are reported to have collapsed completely, but no casualties were reported.
Authorities reported that six people were injured, including five firefighters and a Saudi man, and given medical treatment.
Videos of flames engulfing the heritage buildings in Jeddah's historic town by the Red Sea were circulated on social media.
Though the buildings were old, they were all inhabited, according to a report in Saudi daily Sabq. It added that the fire broke out in a four-storey building and spread out to the other buildings.
Civil defence units evacuated residents from buildings in the vicinity of Al-Balad neighbourhood as a precautionary measure.
Engr Sami Nawar, the city mayor, was quoted as saying that the fire hit the Al Qumsani, Al Ashmawi and Abdel-Aal buildings.
Al-Balad, known for its old structures, is listed on UNESCO's World Heritage site. Its historic centre where the old souqs and 'Bab Makkah' (Arabic for 'gateway to Mecca') are located.