A person who answered the phone at the business at 3940 Falls Lake Road told ABC11 that someone was putting fuel in a boat and it was left running when the explosion occurred.
Deputies said four people - including children - are hurt with burns. None of the injuries appeared to be life threatening.
Pictures from Chopper 11 HD showed the boat next to the gas pump. There was some damage to the vessel, but it didn't appear to be in any danger of sinking.
Durham deputies and fire officials were investigating.