The explosion took place when three people were working on a transformer in the building’s electrical room.
Video shows an exterior wall at the hotel covered in black marks.
One nearby worker heard a “boom” and reported flames and smoke.
He said: “I heard a boom and saw a huge large flame followed by smoke. It shook everybody up.”
One of those hurt sustained major injuries. Two suffered only minor injuries.
Nearby streets have been closed off.'
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