Donald Trump knew members of the crowd at his rally near the White House on 6 January 2021 were armed, but demanded security apparatus be removed to allow them closer, then instructed the crowd to march on the US Capitol, a key witness told the January 6 committee.

According to the witness, Cassidy Hutchinson, the president later attempted to assault an aide who refused his demand that he go to the Capitol too.

Hutchinson, a former aide to Trump and his chief of staff, Mark Meadows, testified in person on Tuesday.

She described how, backstage at the Ellipse shortly before his speech, Trump demanded supporters be allowed in, to fill the area to capacity as his remarks were shown on TV.

The president was warned by a Secret Service official that protesters outside security magnetometers were carrying weapons.

Trump said: “I don’t fucking care that they have weapons, they’re not here to hurt me. They’re not here to hurt me. Take the fucking mags away. Let my people in. They can march to the Capitol from here, let the people in and take the mags away.”

Liz Cheney, vice-chair of the January 6 committee, led questioning of Hutchinson.

The Wyoming Republican presented law enforcement recordings from 6 January 2021 in which officers described protesters carrying AR-15-style rifles and handguns.

Cheney also presented evidence about protesters wearing body armour and carrying bear spray and flagpoles to use as spears.

Cheney said: “Let’s reflect on that for a moment. President Trump was aware that a number of the individuals in the crowd had weapons and were wearing body armour. And here’s what President Trump instructed the crowd to do.”

The committee played video of Trump’s speech at the Ellipse.

Trump said: “We’re going to walk down and I’ll be there with you … we’re gonna walk down to the Capitol.”

The riot that ensued bore out a prediction Hutchinson said Meadows made to her on the evening of 2 January: “Things might get real, real bad on January 6.”

A bipartisan Senate committee linked seven deaths to the riot, which failed to stop certification of Joe Biden’s election victory. The January 6 committee has shown that the vice-president, Mike Pence, came within 40ft of the mob, members of which chanted that he should be hanged.

In video testimony played in earlier hearings, Hutchinson described how Trump responded to such chants: saying maybe Pence deserved it, for refusing to reject electoral college results.

Later in the hearing, Hutchinson relayed an astounding story of the president attempting a violent act himself.

Hutchinson said Tony Ornato, a Secret Service official and deputy chief of staff, told her of a physical altercation in the presidential vehicle, the armoured limousine known as the Beast, when Trump was told he could not go to the Capitol too.

Trump, Hutchinson said, tried to grab the steering wheel, then lunged at the chief of his security detail.