U.S. Rep. Tim Walz headed to Minneapolis-St. Paul International Airport on Monday morning, seeking information about how President Trump's executive order on immigration was affecting the airport and the people trying to pass through it.

But when he got to the airport's customs office, Walz said no one would talk. From behind a glass wall, the customs agents told the Democratic congressman that they'd been directed not to speak to him -- but wouldn't say who gave them that direction. 

A frustrated Walz posted a video about the situation on Twitter, and then spent the day trying to confirm if anyone was being held at the airport. Later in the afternoon, Walz said his staff had been able to confirm that no one had been detained, though he did not know if anyone had been stopped or questioned about their immigration status. 

He said all members of Congress should be able to get information on behalf of their constituents from federal agencies -- and that he was disturbed by the response he received at the airport. The congressman said he'd toured the facility several times and expected that he'd be able to talk to the workers he'd spoken with many times in the past.

"This is not the way government is supposed to work," Walz said. "I want to be clear: No matter what your policies are on this, as an elected representative of the people we have oversight of the executive branch. It's a constitutional issue."

Walz flew to Washington on Monday and said he was working with colleagues in Congress to respond to the president's order. He said he was also trying to sort through reports that college students in his district may have been affected by the new immigration rules. 

"When they say everything is going smoothly and it's fine, that is not the situation with my constituents," he said. "And as an elected representative of Article I of the Constitution, being stonewalled to the point where I don't even know what's going on at the airport in Minneapolis -- that has never happened before."