ATLANTA -- The discovery of two suspicious devices on the campus of Georgia Tech Monday led to the evacuation of some student residential dorms and a terrorism investigation into who left the explosives.

The devices on the Tech campus came a few minutes after another suspicious device, later found to be harmless, was found at a QuikTrip gasoline station, located on Satellite Boulevard at Pleasant Hill Road.

No injuries were reported in either incident, which prompted huge police responses.

Authorities were called to the Tech campus in northwest Atlanta shortly after 9 a.m. after receiving a report of an explosive device that was detonated in a building in the 100 block of Bobby Dodd Way. About 100 students were evacuated from Cloudman and Glenn residence halls while police investigated the devices.

Brian Goldsmith, a student in one of the dorms, said police went door to door to rouse students from the building. Many of the students, some of them still in their pajamas, gathered outside while crews went inside.

"They came around banging on our doors," he said.

Police said two soda bottles fashioned to look like bombs were found in the courtyard of one of the buildings. A janitor found one of the devices and it exploded in his hands as he picked it up.

The janitor was picking up trash in the courtyard when he pulled out the bottle from bushes. The janitor was taken to a local medical clinic for evaluation but suffered no serious injuries, said Tech spokeswoman Amelia Gambino said.

"The Atlanta Police Department and Georgia Tech Police Department take these very, very seriously," Atlanta police Maj. C.J. Moss said. "It's a terrorist act . . . and we expect to identify those responsible and bring them to justice."

Police said neither of the devices contained a detonator, and university officials said they have not received a written or verbal threat. Police still are working to determine what chemicals were in the bottles. The incident prompted authorities to contact the Georgia Department of Homeland Security.

At about the same time police in Atlanta were responding to the Tech incident, Gwinnett officials in Duluth were responding to a suspicious device at QT gas station.

A customer called police after finding the device, described as a mini-flashlight, shortly before 9 a.m. A police robot was dispatched to the scene to handle the package.

Officer Darren Moloney said the device posed little threat to customers.

"It didn't get here by accident," he said, adding that investigators will try to find out where it came from.

Channel 2 Action News reporters Tracy Martinez and Eric Philips contributed to this report.