While city officials breathed a sigh of relief Wednesday after an Inauguration Day free of major chaos or arrests, Capitol Hill buzzed over reports that thousands of ticketed guests were shut out of the ceremonies.

Several Members — upset about complaints from constituents — demanded an explanation for why the Secret Service turned away so many legitimate ticket-holders.

The Joint Congressional Committee on Inaugural Ceremonies sent out a statement of apology and vowed to investigate, though Chairman Dianne Feinstein (D-Calif.) maintained Wednesday afternoon that crowds — not security problems — were to blame.

“People crashed it and security shut it down,” she said, later adding: “There couldn’t have been more police on the scene.”

But those who experienced it firsthand said lines for the blue and purple sections, which were in the coveted West Front viewing area of the Capitol, were disorganized. They added that police were virtually absent and communication was nonexistent.

YouTube videos show crowds of purple ticket-holders on foot stuck in the Third Street tunnel, with the title “tunnel of doom.”

One attorney, who asked that his name not be used because of his work with the government, said he got in line for the purple section at 7:15 a.m. and never moved for three hours.

“There were no cops or anybody giving us any information,” he said. “The only cops we saw were when they tried to drive motorcades through the crowd.”

When asked if officers were sufficiently controlling the massive lines, Feinstein said she believed “everything was done planning-wise.”

But by Wednesday evening, spokesman Howard Gantman said Feinstein had decided to ask the Secret Service to convene all law enforcement agencies involved and report back on whether and why the gate for purple ticket-holders was closed, and why officials directed some ticket-holders to the Third Street tunnel without sending enough officers to handle the crowd.

Much is unclear about how and why people were unable to get into the gates in time. Congressional officials handed out no more tickets than they did for former President George W. Bush’s 2005 inauguration, and gates opened earlier.

The Joint Congressional Committee on Inaugural Ceremonies tentatively chalked it up to confused crowds and a National Mall that quickly filled up.

“Many of the problems appear to have been due to the unprecedented crowds, and a huge flow of unticketed people toward the U.S. Capitol and into the 3rd Street Tunnel from the National Mall, after it had reached capacity very early that morning and was closed to additional unticketed entries,” the statement reads.

It continues: “The JCCIC, U.S. Capitol Police and our federal and local partners will thoroughly examine every aspect of our planning including ticketing, screening, pedestrian flows, gate numbers and placement, to provide a foundation of lessons learned to future inaugural planners, so that they have the information they need to prevent similar problems. We realize how important this inauguration was to so many people and the difficulties they endured to get here, so once again we deeply apologize to those guests who were not admitted.”

Capitol Police officers also said that many people in the lines either had no tickets or fake tickets, bogging up queues that should have been shorter. Matt Tighe, chairman of the Capitol Police Labor Committee, said officers also had to take extra time to screen people wearing winter clothing. “If you take an extra 20 seconds per person to screen them properly, it really starts adding up,” he said. “I don’t think anything went wrong. It was just the sheer volume of people.”

But Rep. Don Young (R-Alaska) called the incident a “failure in planning and organization that must be explained” in a letter to Feinstein he hoped to send today.

“Why was there no form of crowd control in the ticketed screening areas? Why didn’t the planners better mark the areas, provide staff to help direct people or include a way to pass along information?” he wrote. “Why was the screening process so unprepared for the event and why were thousands of people unable to attend the Inauguration despite having tickets to the event?”

Young asked Members to sign the letter in a “Dear Colleague.” A half-dozen had signed it by 5 p.m. Wednesday, and spokeswoman Meredith Kenny said others had expressed interest.

Rep. Vernon Ehlers (R-Mich.) was one of the few who signed it after getting some complaints from constituents, said spokesman Kevan Chapman. “Part of the reason why he wants an explanation is there are multiple explanations right now,” he said. “We’re not sure what to believe.”