The blaze broke out at the shop in Spring Valley on Thursday night and witnesses said they heard a popping sound before there was an explosion.
Two people, including a barbershop employee, were slightly hurt.
Exploding lithium-ion batteries continue to pose fire danger as their popularity increases. One worker said he believes the cause was an overloaded extension cord, but either way, the damage was significant.
Business owners used fire extinguishers from their stores to put out the bulk of the flames before firefighters arrived.
Firefighters from the Hillcrest Fire Company, Monsey Fire Department and New City Fire Department worked together to extinguish the fire.
As the investigation continues, the barbershop remains off limits and the Ramapo building inspector said the business lacked the proper certificate of occupancy and proof of fire safety compliance.
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