Tourists and residents were drawn by the 5am blast and resulting fire at the Momento Apartment and Restaurant in Chon Buri’s Bang Lamung district.
Some suggested the apartment block had been built too close to to the high-voltage power pole, perhaps illegally.
Four fire engines responded and crews spent half an hour extinguishing the blaze.
Police suspect that a short circuit caused the explosion and fire.
The apartment building’s maintenance room and several vacant flats were damaged, but no one was injured.