WASHINGTON (AP) — The hundreds of thousands of spectators at President Barack Obama's second inauguration Monday encountered strict security screening, slow-moving lines at checkpoints and a packed National Mall. But while some inauguration-goers complained they were stalled in getting into the swearing-in ceremony, or had difficulty accessing public transit, law enforcement authorities reported no major security problems from a crowd that was smaller than the record-breaking turnout of 2009.

"There was a lot of lessons learned brought into this one and a lot of pre-planning," said Chris Geldart, the District of Columbia's homeland security director. "I think it went as good as it could go."

Heightened security was evident throughout the nation's capital, from police officers stationed inside subway stations and on street corners to military Humvees that blocked downtown intersections. Spectators navigated through street closures, checkpoints that screened for a wide range of prohibited items, and demonstrators for varied causes. Flight restrictions were in place above Washington and more than 2,000 out-of-town officers were sworn in to work security.

There was no official crowd tally Monday night, but Geldart said it was "definitely above 800,000" and possibly up to 1 million — a large turnout, though still smaller than the 1.8 million who packed the mall for President Barack Obama's first swearing-in ceremony.

Officials had hoped that more signs, plus additional magnetometers, would ease pedestrian congestion and reduce some of the logistical snafus from four years ago.

But even with smaller crowds, there were sporadic reports of slow-moving security lines, including at a gate between Union Station and the U.S. Capitol that came to a halt so a motorcade could pass and barriers could be repositioned. Stuck spectators vented on Twitter that the line did not move for at least a half-hour and that they were redirected to another security gate.

"People were frustrated because no one knew whether they should stay or go," said Ralph Mason, 24, of Tallahassee, Fla., who was at the gate with his girlfriend. He said people in the line received conflicting advice, but he believed officials recognized the confusion and did try to solve it.

"It was a little tense this morning" at some of the gates, acknowledged Metropolitan Police Department Chief Cathy Lanier, who sent additional officers to deal with crowding for people with tickets to the ceremony. "I was getting a little nervous."

Some repeat inauguration-goers said the experience was better than in 2009.

"It's a lot easier because there aren't as many people," said Anita Sutterlin of Middlefield, Conn., who watched the afternoon parade from her perch on the top row of some aluminum bleachers near the White House. She was attending her third inauguration with her husband, Paul.

Others were frustrated in trying to reach their destination. Cheryl Tate, 52, of Flint, Mich., and her friend Karen Pugh, 43, gave up hope of getting into the mall and decided to turn around after trying to walk from RFK Stadium, in southeast Washington, where their bus had parked. They ultimately found a free shuttle back to the stadium, where they waited for their group in anticipation of a long drive back to Michigan.

"We didn't see anything, unfortunately," Tate said, adding that others on their tour bus had been luckier.

A smattering of protest groups occupied spots along the Pennsylvania Avenue parade route, but the demonstrations largely were directed at long-running national and international concerns rather than at policies specific to the Obama administration.

The U.S. Capitol Police arrested three people, including a demonstrator who refused to come down from a tree and was shouting and chanting, said spokesman Shennell Antrobus. D.C. police hadn't reported any arrests of protesters as of Monday afternoon.

A few dozen protesters with the ANSWER Coalition, a peace and social justice coalition, gathered at Freedom Plaza near the White House to honor the late civil rights leader Martin Luther King Jr.'s legacy and call for jobs, not war. Brian Becker, the coalition's national coordinator, said the group focused on messages that would resonate with a pro-Obama crowd. In addition to a poster focusing on King's legacy and jobs, protesters had signs saying "Indict Bush Now" and "Drone Strikes (equals) War Crimes."

John Diamond of Arlington, Va., handed out flyers inviting people to a "disinauguration ball" as people exited the inauguration ceremony. The flyers, which said "Not my president," invited people to an event later Monday in Virginia. Diamond, who didn't vote in this election, said he wants to encourage peace and opposes the drone attacks the president has authorized.

"We're just out here celebrating freedom and trying to get people to think about the fact that we don't need violence to control people or dictate the behaviors of other people and we should start looking for alternatives," Diamond said.

Another activist, Malachy Kilbride, said that while he and other protesters with the Arc of Justice Coalition were pleased Obama had broken the race barrier by winning the presidency, "that does not negate the fact that we are very upset with issues like the bailout of the banks, corporate influence in government, big money in politics."

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Associated Press writers Matthew Barakat, David Dishneau and Jessica Gresko contributed to this report.

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