LINTHICUM, Md. (WJZ) –Security failures at the nation’s busiest airports.

Undercover agents find the TSA missed dangerous explosives almost every single time.

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Now, passengers are worried and the government is taking action.

Christie Ileto has more on the serious gaps that were found.

The feds wouldn’t say which airports this happened at, but officials say the fact this happened multiple times only exposes vulnerabilities in our security.

Posing as passengers, undercover investigators smuggle dangerous items through security.

Sixty-seven out of 70 times fake explosives and banned weapons go undetected at Transportation Security Administration checkpoints in airports across the country.

How did this happen?

“This shows there are serious vulnerabilities in the screening process,” University of Maryland Homeland Security expert Michael Greenberger says. “We go through this intense screening, take off your shoes, take off your belt — then you find out if someone is clever they can evade the system.”

In one test, TSA agents didn’t even find a mock explosive taped to an undercover agent’s back during a pat down.

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The bomb parts mirrored those used in the underwear bomb which almost exploded aboard a Christmas Day flight in 2009.

Christie: “Do you feel less safe?”

Traveler: “Man it makes me feel less safe.”

The Department of Homeland Security is now investigating, telling WJZ immediate changes have been ordered including a revision of TSA’s operating procedures for screening, training for all TSA officers and the retesting of screening equipment.

But that’s little comfort to travelers.

“If that was a real situation, we would be in trouble,” Keaira Lashae said at BWI Monday. “That’s really scary for someone like me. I travel every month.”

But this was just a test, will be as lucky the next time?

This isn’t the first time this happened.

In 2013, an undercover agent has a fake bomb hidden on him, went through a pat down — and was never caught.

DHS says last year, the TSA screened a record number of passengers, while seizing a record number of prohibited items.

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