Rep. Chris Van Hollen (D-Md.) sent a letter to Sen. Dianne Feinstein (D-Calif.) Thursday expressing “deep concern” that thousands of ticket holders were shut out of President Barack Obama’s swearing-in ceremony.

Van Hollen is the latest in a string of Members who have demanded an explanation for why officials prematurely closed off the entrances to the blue and purple viewing section — two coveted spaces on the Capitol’s West Front.

Feinstein, chairman of the Joint Congressional Committee on Inaugural Ceremonies, has apologized and asked the Secret Service to investigate what went wrong. In his letter, Van Hollen wrote that he strongly endorsed the review.

“My office has received many calls and emails from constituents expressing their disappointment and heartbreak over not being able to witness this momentous occasion,” he wrote. “And to be clear, these are individuals who did everything they were supposed to do.”

He added: “And worse yet, they were kept in the dark — deprived of information — as the hours passed and their hopes of seeing history in the making slipped away.”

Ticket holders have described the scene Tuesday as chaotic, with disorganized lines and few officers to control it.

At one point, officials directed thousands of people to the Third Street tunnel, where they waited fruitlessly while the Secret Service, meanwhile, apparently closed the entrance.

Feinstein, police officials and the Joint Congressional Committee on Inaugural Ceremonies have offered a few explanations, attributing the trouble to unprecedented crowds and an influx of unticketed people into ticketed lines.

But Van Hollen wrote that while he appreciate the “extraordinary planning” for the event, “I am baffled by the break down, on such a broad scale, of the processing of people who followed the rules and came only to see, hear and be part of this remarkable moment in our nation’s history.”