Police do not yet know the number of guns stolen from a Castle Rock gun store that was burglarized around 2:00 a.m. Tuesday, but investigators say the burglary could be linked to a string of other, similar thefts in Colorado.

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is investigating four burglaries where at least 45 guns have been stolen from licensed dealers since April 18.

On Tuesday, suspects drove to DFC Guns at 1155 Park St. in a stolen Jeep Cherokee. They tied straps to the Jeep and used those straps to pull open the front doors of the building, but police could not immediately report how many guns were taken.

“All had masks or clothing cover their faces," Tim Ratcliff said, an investigation Sgt. for Castle Rock Police Department. "One had a Shrek mask on.”

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This burglary comes a week after an attempted break in, also at DFC Guns – when suspects drove a Jeep into the building but were unable to steal any weapons.

The Castle Rock police believe the two incidents are connected, and ATF is investigating the possible links between three other Colorado burglaries in the last two months.

The first, targeting Springs Armory in Colorado Springs on April 18, resulted in 22 guns stolen by “four or five masked suspects.”

Then, on May 24, Triple J Armory in Littleton was robbed for the second time in a year. The suspects used a vehicle to break into the building and steal 11 handguns.

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Just two days later, suspects attacked the Machine Gun Tours in Lakewood, stealing 12 semi-automatic rifles and handguns.

The ATF says that all four of these burglaries included a “smash and grab” approach where the suspects use a vehicle to break into a gun store, run in and apparently grab as many guns as possible in under 5 minutes.

The ATF tracks any loss of guns by licensed dealers, including those that were stolen or that the dealer simply lost.

Last year, licensed gun shops around the country lost 9,113 guns, and another 9,281 were stolen. In Colorado, 273 guns were stolen from licensed dealers in 2016 - a 10-year high - and gun stores lost 46 more guns. This marked a dramatic rise in gun thefts over 2015, when only 121 guns were stolen from Colorado stores.

Nationally, there are no requirements for securing a gun store – unlike the requirements that exist for pharmacies or explosives. States could pass their own rules for gun store security – but the ATF says just California and Connecticut have such regulations. Instead, the ATF releases guidelines that encourage gun store owners to maintain updated inventories and invest in security systems.

“Those firearms aren’t going to be sold to a law abiding citizen," Ratcliff said. "They are going to a criminal.”

The ATF is offering a $10,000 award to anyone with information about these four gun store burglaries in Colorado.

Over the last year, the ATF has made 15 unrelated arrests recovering 55 stolen guns.