Wanchai "Ae" Boonchongsang, the manager of Pepper's in Laguna, said he arrived at SuperCheap around 9.15pm to do some shopping. Reports say the fire, which demolished the entire building, started around 9.30pm.
"One of the staff told me there was a fire, so I looked and it was very small. Then I went to the cashier and on the way out I told some of the staff at the front of the store about the fire.
"It didn't look like a big fire. I thought the staff would take care of it, because it wasn't that big," Mr Wanchai told The Phuket News.
"Then the smoke started to come and everyone started to run away. Some people paid for their shopping and then ran away, leaving their shopping at the cashier. It was very crazy. They were crying and screaming.
"There was an old man walking toward the fire inside the store. I'm not sure if he's alive or dead, I hope he's alive. I hope someone got him out. It was so scary.
"It came so fast, it was very, very fast. Less than 10 minutes and it burnt up everywhere. There was no alarm or anything to tell the customers, there was no warning."
Mr Wanchai said at the time there were not many customers at the store, but there were a lot of staff working.
He said the fire started in the plastics and foam area of the store.
Mr Wanchai said he was "sure" there would be injuries or fatalities. So far there have been no confirmed reports of any injured or dead.
After he left the store he went to his car and drove away, stopping on the bypass road to see the smoke. He said he was "shocked".