MADISON, Wis. -- Police are investigating a bomb threat that forced them to evacuate the state Capitol in Madison Tuesday afternoon.

State Department of Administration spokeswoman Carla Vigue said 911 operators received the threat, but she doesn't know precisely when.

Capitol police officers searched the building for a suspicious man with a bag before the evacuation began around 3 p.m. Tuesday.

Officers swept the building but found nothing. Vigue said they reopened the Capitol for workers about 90 minutes after the evacuation began. Full public access is expected to resume Wednesday morning.

Workers inside the Capitol said they aren't taking any threats lightly.

"With all the terrorist scares lately, it's in the back of your head, obviously, with what just happened in Detroit. You work in a government building, and a lot of people are unhappy with the government right now. It's always in the back of your head. You don't necessarily think anything bad is going to happen, but when they tell you to leave, you leave," said Ian Shannon-Bradley, who evacuated from the Capitol.

Vigue said the investigation continues.

She said Gov. Jim Doyle was en route to Madison from an event in Oconomowoc when he was told of the threat. The governor went to his mansion rather than his Capitol office.

Just as the Capitol was reopened, Madison police said a customer at a Starbucks near the Capitol reported a suspicious item, triggering a brief evacuation and another search by a K-9 unit and the bomb squad.

"Since the K-9 did not alert, they elected to send one of their (bomb squad) members inside. That person was able to look inside the suspicious package and come and give us a report, which was (that it was) somebody's sleeping bag," said Sgt. Jen Krueger Favour, of the Madison Police Department.

The sleeping bag appeared to be wrapped in plastic and was tied with rope, WISC-TV reported.

No bombs or devices were found in either location, but officials said they take every threat seriously.

"As far as people forgetting belongings in a coffee shop, it does happen. This one just happened to look rather suspicious, and that's why we took the precautions that we did to make sure that everybody was safe," Krueger Favour said.