WHITTIER (CBSLA.com) – Detectives are investigating whether three robberies that occurred over three straight nights at Verizon stores in Los Angeles County this week are connected.

The robberies occurred in Granada Hills, West Los Angeles and Whittier, according to Los Angeles police. The suspect or suspects were wearing ski or construction masks. In two of the robberies the suspects were armed. In the third, the suspect claimed to have a gun.

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Tens of thousands of dollars’ worth of iPhones were stolen, police said. No one was hurt.

All three robberies occurred around closing time. The first happened Monday night at a store in the 18100 block of Chatsworth Avenue in Granada Hills. The second took place Tuesday night in the 11800 block of Santa Monica Boulevard. The third happened Wednesday night at Norwalk and Beverly Boulevards in Whittier.

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In the Whittier robbery, a single suspect entered the store, claimed to have a gun, and then went into a back room and stuffed about 50 iPhones into a duffel bag.

Detectives are unsure if the same group is responsible for all three robberies, police said.

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Both the LAPD and Whittier police are investigating. Detectives told CBS2 the suspects likely have the skillset to unlock the iPhones and sell them overseas at a price of $500 to $600 each.