DENVER -- Protesters wearing jail-style jumpsuits and black hoods over their heads marched down the 16th Street Mall in downtown Denver on Monday, chanting "Stop the torture, stop the war."

The protesters, estimated at several hundred, were at a rally at Civic Center Park near the state Capitol when they began pouring down the mall at midday, hours before the Democratic National Convention was to start.

Some were dressed like inmates at the infamous Abu Graib prison in Iraq.

They said they were protesting U.S. detention of people they called political prisoners, including American Indian activist Leonard Peltier. Peltier is serving a life sentence for killing two FBI agents during a 1975 standoff on the Pine Ridge Indian Reservation in South Dakota.

Some of the marchers said they were headed toward the federal courts complex several blocks from the Capitol. They briefly walked in two lanes set aside for shuttle buses on the mall, but they got back onto the broad walkways at the direction of police.

Earlier, a small group of protesters marched to the demonstration zone outside the Pepsi Center, where the convention will be held, complaining they are being treated like political prisoners.

It was the first time members of the Recreate 68 Alliance had visited the fenced-off zone, and they vowed not to return because they oppose the limits on where they can demonstrate.

Protesters derisively call the 47,000-square foot zone the "Freedom Cage." It's separated from the parking lot around the convention hall by metal fences atop concrete barriers.

They complained it is about 700 feet from the Pepsi Center -- too far for them to be seen or heard by delegates.

"We're being treated by the city of Denver and the Secret Service like political prisoners, like pariahs," said Recreate 68 organizer Mark Cohen.

Cohen and his wife, Barbara, each wore a red inverted triangle similar to the type political prisoners in Nazi Germany were forced to wear.

"We're going to stay here for just a couple of minutes to state our disgust with this abomination, the way the city and Secret Service are tearing the Constitution of the United States to shreds and then we will leave," Mark Cohen said.

Holly Heiman, 40, of Green Mountain Falls, was among those who walked from a downtown pedestrian mall to the demonstration zone. She said she wanted to show her opposition to what she believes is an oppressive government that won't change no matter who is elected.

"It's kind of shocking there aren't more people" protesting, Heiman said.

She blamed the small turnout on "cops on every street corner" and all the publicity beforehand about security.

A signup sheet for speakers at the protest zone had a number of fake signatures and comments such as, "J. Stalin -- This is awesome" and "G. Washington -- You can't cage freedom."

At one point about 30 lost volunteers, wearing credentials and green T-shirts, wandered into the protest area in search of the Pepsi Center. They refused the protesters' literature.