Just when folks at Augusta's Maine Revenue Services thought they'd be able to clock out and go home for the day, an unnerving situation began to unfold.

What happened?

Things got tense just minutes before 5 PM. A person in the building noticed a suspicious package and opened it. They then realized something didn't feel right, and brought the package outside, while calling the authorities.

Read More: Greg Wilfert, Maine's 71-year-old Lifeguard, Survived A Shark Attack

The response was immediate!

According to the Maine Department of Public Safety, the Capitol Police were first to respond. Then the Maine State Police Bomb Squad was called in to investigate the building located at 51 Commerce Drive in Augusta.

The Augusta Fire Department and the 11th Army National Guard Civil Support Team also arrived to lend their support.

"Out of an abundance of caution, the building was evacuated while the package was evaluated... Through X-ray imaging and presumptive field testing, investigators determined there were no explosive or biological hazards inside the package. No injuries were reported."

Authorities are still looking into the matter.

It's still unclear what the package contained, who it belonged to, or how it got into the building.

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Maine Bomb Squads are a specialized group of law enforcement.

The Maine State Police Bomb Squad is one of 3 FBI-accredited Hazardous Device Units (as they're often called) in Maine.

This five-member team of specially trained technicians has been around, according ot the state of Maine website, since 1994. Their duties include the actual inspection of suspected explosive packages or devices.

Members of the team have to pass a number of intense tests to even be selected to train to become a Bomb Squad member.

They start with a basic 18-week law enforcement training program, along with another 3+ months program at the Maine Criminal Justice Academy.

Read More: Inside The Week Of Maine's Bomb Squad And Explosive Finds

They must then pass physical tests, background checks, and a polygraph test, along with an oral exam.

There's also a requirement that candidates spend some years as Maine State Troopers first. Only after that will one even be considered to sit for the Bomb Squad testing.

"Following selection, members undergo rigorous training to become certified bomb technicians, often through the FBI Hazardous Devices School."

Maine's other 2 FBI-accredited Hazardous Device Units are run by the Bangor Police Department and the Portland Police Department.