The Democrat-led impeachment investigation into Donald Trump was delayed for around four hours after a group of Republicans stormed the closed-door evidence session with a Defense Department official.
Lawmakers said the move compromised national security because some of the Republicans brought electronic devices into a secure room.
The interview with Laura Cooper, a senior official who oversees Ukraine policy, restarted after checks by Capitol security officers.
Democrat Debbie Wasserman Schultz said she had just walked into the room when the Republican lawmakers blew past Capitol police officers.
"Literally some of them were just screaming about the president and what we're doing to him and that we have nothing and just all things that were supportive of the president," she said.
A series of diplomats have been interviewed in the impeachment probe in what is called a Sensitive Compartmented Information Facility (SCIF).
It is a secure room where members can hear classified information with a strict ban on electronic devices.
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