No injuries were reported in the blaze at the Tropicana Casino and Resort, which broke out on the sixth floor just before 4:30 a.m.
But it forced officials to evacuate the casino floor for about 20 minutes. An estimate on how much money the casino may have lost due to the gambling disruption was not immediately available.
Atlantic City Fire Chief Dennis Brooks told The Press of Atlantic City that the fire apparently started in an outdoor planter and then burned through the facade and into a wall. But he said the investigation was ongoing.
The blaze, which was brought under control in about 40 minutes, caused an estimated $30,000 to $50,000 in damage. That includes structural damage to the building's exterior and water damage to utility closets and stairwells on the fourth and fifth floors.
Crews will also have to repair or replace wiring and other mechanics that were exposed or disrupted when firefighters had to break through the wall to get to the source of the fire.