Hundreds of badges, credentials, cell phones and guns belonging to Department of Homeland Security employees have been lost or stolen in recent years -- raising serious security concerns about the potential damage these missing items could do in the wrong hands.

Inventory reports, obtained by the news site Complete Colorado and shared with FoxNews.com, show that over 1,300 badges, 165 firearms and 589 cell phones were lost or stolen over the span of 31 months between 2012 and 2015.

The majority of the credentials belonged to employees of Customs and Border Protection (CBP), while others belonged to Immigration and Customs Enforcement (ICE) and U.S. Citizenship and Immigration Services (USCIS) employees.

The lost or stolen guns also mostly belonged to CBP employees, though others were cited as belonging to TSA and ICE workers. The agencies all fall under DHS. 

The missing badges and guns suggest a shocking lack of security from federal law enforcement officers and represent a significant security risk, experts say.

“It’s scary that you’d have that number of credentials out there that someone could manipulate,” Tim Miller, a retired Secret Service special agent, told FoxNews.com.

While Miller said the phones are likely to have enough protocols in place to prevent them from being used for nefarious purposes, the badges and credentials are an entirely different matter and could allow access to sensitive areas such as cargo.

“The thing that’s particularly concerning is that if you get real credentials, it’s very easy to manipulate them, and you’ve got someone else’s picture on what law enforcement would see as valid," Miller said. "Then you factor in terrorism, it’s a significant concern that people would run around with authentic credentials and be able to access areas they wouldn’t otherwise be able to access.” 

When reached for comment, DHS did not dispute the inventory report data -- which Complete Colorado, a Colorado-based online news site, had obtained via a Freedom of Information Act request. The reporter who obtained the data also works with Denver-based free-market think tank the Independence Institute. 

In a statement to FoxNews.com, a DHS spokesman said they strive to be “good stewards of government resources” and have improved oversight and reduced the number of lost or stolen items over the past few years.

“If a credential holder loses or has their credentials stolen, the holder must report the incident to their supervisor and credential issuance office immediately,” spokesman Justin Greenberg said. “Once the incident has been reported, this information is entered into appropriate DHS and law enforcement databases, which disables use of the lost or stolen item.”

He also noted that DHS encrypts all mobile devices, laptops and tablets.

Miller said officials need to be doing more, considering the sheer number of guns and badges that have been lost or stolen.

Lawmakers also have expressed concern about the safety of DHS property in the past. In December, the Senate Commerce, Science, and Transportation Committee approved legislation that would tighten screening of TSA workers, review security protocols and increase fines and enforcement requirements related to missing credentials.

The legislation was put forward after members of the committee wrote to TSA officials in March expressing concern about reports of unaccounted TSA badges, and the reported use of badges to bypass security checkpoints.

“Officials entrusted with protecting the American public cannot consider the loss of sensitive items normal or routine," Sen. John Thune, R-S.D., chairman of the committee, told FoxNews.com.

"When the Commerce Committee looked at lost and missing airport security credentials, we discovered that existing rules weren’t being effectively enforced. Mistakes happen, but if we don’t work to eliminate them and insist on accountability, then we’re left with unacceptable risk,” Thune said.

Adam Shaw is a Politics Reporter for FoxNews.com. He can be reached here or on Twitter: @AdamShawNY.