People organizing demonstrations related to the Republican National Convention said that members of the St. Paul police department and the Ramsey County sheriff's department had detained dozens of people on Friday night inside a building in St. Paul that was being used as a protest-planning headquarters.

People who had been inside the building said that officers entered shortly after 8:30 p.m., saying they had a warrant and instructing the occupants to lie on the ground.

"They handcuffed all of us," said Sonia Silbert, 28, from Washington. "They searched everyone."

At 11 p.m., police officers stood in front of the building. People who emerged one by one told similar stories about what had taken place inside. They said they had been searched and questioned and photographed before being released. Jordan Kushner, a member of the National Lawyers Guild, said the two-story brick building had been rented by a nonprofit organization and was being used by several groups planning protests.

People who had been inside said that teach-ins and legal training had been conducted there and that the space was also a repository for such items as computers and bicycles. Mr. Kushner said he believed that the police had read a warrant aloud but said he had not seen the document.

The R.N.C. Welcoming Committee, one of several groups organizing demonstrations, issued a statement late Friday night that was read aloud outside the meeting place by a woman named Sarah Coffey. She said that the officers had cited fire violations as the reason for their visit and added that they had "detained over 50 people in an attempt to pre-empt planned protests."

Spokesmen for the St. Paul police could not immediately be reached for comment.

By COLIN MOYNIHAN, The New York Times, August 30, 2008