Robbers hit 3 Chicago 7-Eleven stores in less than 30 minutes on Monday

It's either a very strange coincidence – or a coordinated robbery spree targeting convenience stores in Chicago.

On Monday morning, three stores were robbed in the city's Loop neighborhood in a 30 minute crime spree.

The first robbery happened at a 7-Eleven on East Lake near Millennium Park at 8:29 a.m. Four men came in with weapons, stole money, took off in a black vehicle.

Just five minutes later, four guys wearing masks and hooded sweatshirts came into the 7-Eleven on Wacker near Wabash and grabbed money and merchandise.

Then, 20 minutes later, four guys robbed the 7-Eleven on South State at Jackson

Earlier this month, Chicago police warned convenience store workers in the Loop about robbers after two shops were targeted.