WASHINGTON — Metro says it has instituted action to maintain security after a set of its keys were stolen.

The theft occurred where thieves are rarely known to strike.

Arlington County Police say thieves grabbed several items, including the Metro keys, from an Arlington County fire engine that had responded to an emergency in Crystal City early Thursday morning.

Video surveillance captured images of two men in dark-colored clothing and wearing masks, according to Arlington County police spokesman Dustin Sternbeck.

Metro spokesman Dan Stessel declines to say what the keys unlock but he says Metro Transit police have taken steps to ensure that the system is not compromised.

Fire engines responsible for responding to Metro emergencies can carry keys to external gates on Metro property, large fan shafts that access Metro rail tunnels and electrical and control panels.

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