Thousands of people poured into the state Capitol following a surprise vote by state Senate Republicans to pass elements of a bill taking away most collective bargaining rights from public workers.
Police gave up guarding one of the main entrances to the Capitol on Wednesday night, allowing people to come in unabated.
Protesters began pouring into the building shortly before its 6 p.m. closing time to witness the Senate hastily pass parts of Gov. Scott Walker's budget repair bill.
Capitol security repeatedly asked protesters to get off of second floor walkways because they were concerned over their structural security.
Department of Administration spokesman Tim Donovan said the goal of police is to ensure people's safety.
Donovan said that anyone inside the Capitol building Wednesday night was in violation of a court order to leave the building when it is closed. He said that no official business was going on after the Senate's vote.
The Senate's vote sparked the latest protests, as protesters climbed through windows and streamed into the Capitol just after 8 p.m., joining hundreds already inside the Capitol, a crowd that did not leave when the Capitol closed.
"This is illegal, what they tried to do today, and we're going to stay in this building as long as it takes because we know that tomorrow at 11 a.m., I don't even know how the situation is going to be. We might not even get a chance to be here," said Ayeshah Emon, a member of the Teaching Assistants' Association.
The feeling among protesters at the Capitol Wednesday night is that they weren't giving up the fight, WISC-TV reported.
"I just heard, 'Get to the Capitol, they're going to try to pass a bill and just get in and support us, support the working class of Wisconsin,'" said Laura Glass, a member of Madison Teachers Inc.
Corrections officer Eric Osse said he is furious over the surprise move in the Senate passing non-fiscal items in the budget repair bill.
"Right now, I'm just feeling betrayed," Osse said. "It's just not the right way to go about politics."
"I guess I have to say I'm disappointed, greatly disappointed. I'm not surprised," Glass said.
Donovan said that they've received reports of protesters entering through broken windows and getting through doors, but they don't know where the damaged windows are. Donovan later said that those reports of broken windows and doors may not be true. Donovan said he walked around the building and didn't see any broken glass outside.
The Capitol has been the scene of protests for three weeks, with hundreds of demonstrators spending the night until last week when they left under a court order. But minutes after Wednesday's vote they surged back into the building, making signs, pounding drums and moving food into the Capitol Rotunda, just as if they'd never left.
Stay tuned to WISC-TV and Channel 3000 for continuing coverage.