In chilling new testimony about the January 6 attack on the US Capitol, the investigating House committee showed that members of the Secret Service detail for the vice-president, Mike Pence, so feared for his and their safety that they “screamed” that other officials should say goodbye to their families.

A White House national security official whose identity and voice was obscured described the calls in testimony played by the January 6 committee in a public hearing on Thursday night.

The official was asked why, after a mob that Donald Trump sent to the Capitol attacked Congress in an attempt to stop Pence certifying Joe Biden’s election win, staff at the White House officially recorded that, “Service at the Capitol does not sound good right now”.

The official said: “The members of the VP detail at this time were starting to fear for their own lives. There was a lot of yelling. There were a lot of very personal calls over the radio, so it was disturbing. I don’t like talking about it.

“There were calls to say goodbye to family members, so on and so forth … for whatever reason it was on the ground, the VP detail thought this was about to get very ugly.”

Such terrified and panicked messages were relayed from the Capitol around the time Trump tweeted to his supporters a now infamous 2.24pm message in which he did nothing to calm the riot.

The then president said: “Mike Pence didn’t have the courage to do what was necessary.”

News that members of the Secret Service thought they were going to be killed by the pro-Trump mob comes amid considerable tension between the Secret Service and the January 6 committee.

The committee served the agency with a subpoena for all text communications on the day before the Capitol attack and the day itself. The Secret Service said the messages had been wiped. It subsequently delivered just one message to the committee.

Nine deaths have been linked to the Capitol riot, including law enforcement officers who died by suicide. Nearly 900 people have been charged, some with seditious conspiracy. The committee is attempting to show grounds for criminal charges against Trump himself. The Department of Justice would have to bring any charges.

In the primetime Thursday hearing about events on January 6, the national security official said: “I think there were discussions of reinforcements coming but again it was just chaos, they were just yelling.

“If they’re getting nervous and they’re running out of options, it sounds like we came very close to either Service having to use lethal options or worse.

“At that point I don’t know? Is the VP compromised? I don’t know. We didn’t have visibility. But if they’re screaming and saying things like ‘Say goodbye to the family’, the floor needs to know this is going to whole ’nother level soon.”

Referring to controversy over the missing Secret Service texts, the presidential historian Michael Beschloss tweeted: “For all of those Secret Service agents who seem to love and venerate Trump, look at how he did nothing to defend Mike Pence’s agents on January 6 as they called their frightened families to say goodbye forever.”