Part of a Minneapolis-St.Paul International Airport terminal was briefly evacuated and the upper airport roadway closed on Saturday after an unattended bag tested positive for explosives, a spokeswoman said.

The north end of the Lindbergh terminal was evacuated at about 1:20 p.m., and the roadway shut down while a bomb squad from the Bloomington, Minnesota, police department investigated, airport spokeswoman Melissa Scovronski said.

"It was an unattended backpack on one of the airline ticket counters, on the scale," she said. "One of our officers decided to swab it, and it came back positive for explosives." The bag, which had been left on a scale at a ticket counter, also tested positive when a Transportation Security Administration agent swabbed it, Scovronski said.

The scene was cleared and the terminal reopened about 40 minutes later, she said, after no explosives were found.

Airport police were trying to determine who left the bag on the scale and why it tested positive, Scovronski said.