It took only seconds to detonate the suspicious device that closed the Downtown Connector and caused two hours of traffic nightmares Monday afternoon. Although it wasn’t known what the device was, the southbound lanes quickly re-opened, and the northbound lanes followed after the area was deemed safe.

The roads were open well before 5 p.m., but the traffic backups took time to clear. Late Monday, Atlanta police said the device wasn’t explosive, but didn’t elaborate on what it was.

A passerby called 911 after spotting the tube-shaped package duct-taped to the east side of the 14th Street bridge shortly after 1 p.m., forcing police to close the Downtown Connector just before 2 p.m. Two hours later, the Connector remained closed.

Motorists were strongly advised to avoid downtown Atlanta, and those already driving were being forced off the interstates, causing traffic backups around downtown. And rush hour hadn’t even officially started.

The device was detonated at the bridge about 3:55 p.m., according to the Atlanta Police Department. Engineers then inspected the 14th Street Bridge and determined it was safe, a DOT spokeswoman said.

Dozens of drivers were temporarily stuck in place in both directions on I-75 and I-85 and were being diverted to I-20 eastbound and westbound. That led to backups on many cross streets throughout the city.

Just after 1:40 p.m., Officer Kim Jones with the Atlanta Police Department told The Atlanta Journal-Constitution that a “tube-shaped object” was found duct taped to the east side of the bridge at the base of a green post.

An hour later, a bomb squad truck was sitting in the middle of the northbound lanes on the Connector, halfway between 10th and 14th streets. But the interstate was empty of other travelers, an eerie sight for Atlanta at any time of day.

Those using mass transit, such as Gwinnett County buses, were being advised of delays due to interstate closures. Six MARTA bus routes were diverted, a spokesman for the transit said. Train stations were not affected.