CHICAGO (CBS) — Police are investigating thefts of propane tanks on the city’s North Side.

As WBBM Newsradio 780’s Dave Marsett reports, Belmont Area police detectives have issued an alert to gas stations, warning that thieves are cutting locks to metal cages and stealing propane tanks stored inside.

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LISTEN: Newsradio 780’s Dave Marsett reports

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Police are advising business owners to check the locks on their metal cages daily, upgrade to a hardened steel padlock, make sure surveillance cameras are in good working order, inform other business owners about the thefts, and immediately report any thefts to police.

Belmont Area detectives’ jurisdiction stretches from the Chicago River’s Main Branch downtown all the way north to the Evanston border, and from Lake Michigan west to the Chicago River’s North Branch and the North Shore Channel. Police have not specified where in that expanse the thefts have been occurring.

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The Sun-Times Media Wire contributed to this report.