Up to 30 firefighters fought to bring a blaze at a shop in Rainham under control.
The fire broke out at Rochester Wines in High Dewar Road at 10.30pm yesterday and it was initially feared people were trapped in the flats above.
The blaze had started in a single-storey storage area which goes across the back of the shop and the car battery shop next door.
Medway crew manager Kev Chapman said: "When we arrived there were lots of people in the street and flames about 20ft high at the back of the shops.
"There are seven flats about the shops and there were only three people accounted for. I went banging on the doors of the flats above but some of the doors were locked. So our priority was going in with breathing apparatus to check the flats.
"At the same time we were trying to suppress the fire at the rear."
"Once we had ascertained there was no-one in the flats, all our assets were put into stopping the fire."
A woman who did not wish to be named said she saw all the fire engines at around 10.30pm.
She said: "Everyone including all the families managed to get out safely, they think the fire started in the back and the place is completely ruined."
VIDEO: Firefighters outside Rochester Wine in Rainham, from Battery Specialists South East
The owners of Rochester Wines are reported to have "lost everything" in the blaze and the battery shop has been badly affected by smoke damage.
Six fire engines were at the scene at the height of the blaze which was brought under control by 1am. But crews remained at the scene until 5am, checking for hot spots.
Crew manager Chapman added: "We used fans to chase the fire out the back of the building.
"There is damage to the inside of the convenience store but we managed to stop the fire from spreading inside the battery shop."
Smoke damage has also affected the flats.
The owners of the battery store have thanked firefighters for their efforts.
Battery Specialists Southeast posted on their Facebook page this morning: "As you are no doubt aware by now a huge fire broke out in the shop next door to us.
"We have been extremely lucky to say the least. We have extensive smoke damage but all stock, fixtures and most fittings look safe, we will know more this morning.
"We will be open today to start the massive clear up and expect to continue business as usual whilst there.
"Please do not hesitate to continue using us for your battery needs, and even though myself and Terry have a huge job on our hands, we assure you of our best attention at all times.
"Our sincere sorrow goes to our fantastic neighbours at Rochester Wines who have lost everything.
"Our grateful thanks go to Kent Fire Brigade for bringing things under control asap, and above all else were grateful that everybody in the flats above got out safely."
The cause of the blaze is now being investigated by police and the fire service, but it is not thought to be suspicious.