Bomb Sat in Detroit's McNamara Federal Building

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In what appears to be a major security breach, components for a live bomb were allowed to remain in the federal building in Detroit for three weeks before the bomb squad was called in to remove it.

The Detroit Police Department bomb squad was finally called in March 18 to remove the device in the McNamara Federal Building, which houses the FBI, IRS and offices for Sen. Carl Levin. The pipe bomb device had apparently been discovered three weeks earlier by a building guard.

"A contract guard apparently saw this package outside on Feb. 26th," according to David Wright, president of the American Federation of Government Employees Local 918, which represents the Federal Protective Service Employees.

"Against all security protocols -- an unattended package should be treated with extreme caution -- he picked up that package and took it inside basically on the premise of 'lost and found' property. And apparently stored it. That was on Feb. 26. On March 18th, last Friday, someone got the idea to x-ray the package. At that point wires were seen... and it turned out to be a bomb."

The contract security guard has been suspended and in the coming days a special training team will be deployed to Detroit to re-train the building's security personnel on proper protocol, according to Chris Ortman, spokesman for Federal Protective Service.

"FPS will continue to review the circumstances of this incident and take appropriate action with the contract service provider to ensure that proper protocols are followed," he said.

Following the Oklahoma City bombing in 1995 and concerns about terrorists, federal buildings across the U.S. got increased security including metal detectors.

But a 2009 U.S. Government Accountability Office sting saw congressional investigators smuggle bomb components past screeners at a federal building.

ABC News obtained video of the sting -- and it took just 27 seconds to get a device past security. The GAO investigator later assembled a bomb in the restroom, and then walked around the facility undetected. In all, the GAO was able to penetrate each of 10 of the undisclosed federal buildings it tested across the United States.

Watch that report from World News here.

"It's stunning. It's shocking," Sen. Joe Lieberman, I-Conn., the chairman of the Senate Committee on Homeland Security and Governmental Affairs, told ABC News after the GAO sting. "It just says that basically some people have forgotten the lessons of 9/11," he said.

At the time, the Federal Protective Service, a part of the Department of Homeland Security, was responsible for securing more than 9,000 federal buildings and, among other employees, utilized 15,000 contract security guards.

Wright has been in Washington lobbying for more funding for FPS - he'd like to see fewer contract guards and more career FPS guards. He called the current system a "farce."

The Detroit incident is currently being investigated by the FBI's Joint Terrorism Task Force in Detroit. The priority is finding out who left behind what a source is describing as a pipe bomb, which could have injured people nearby had it detonated. And a number of security questions have to be addressed as well including:

How was the device smuggled into the building?

Were magnetometers and x-ray machines properly used?

Why did the security guard not follow procedure?

The bomb components are being examined at the FBI's Quantico laboratory by forensics experts.