All three officials agreed that there appeared to be a level of co-ordination and planning from the crowd.
Mr Sund said that pipe bombs that were placed at the edge of the security perimeter appeared to be intended to draw law enforcement away from the Capitol building.
"When the group arrived at the perimeter, they did not act like any group of protesters I had ever seen," said the 30-year police veteran.
"A clear lack of accurate and complete intelligence across several federal agencies contributed to this event and not poor planning by the United States Capitol Police," he added.
media caption'This was the worst of the worst'
Capitol Police Captain Carneysha Mendoza described the clashes, telling lawmakers that she has chemical burns on her face from attackers that still have not fully healed.
"Of the multitude of events I've worked in my nearly 19-year career in the department, this was by far
"We could have had 10 times the amount of people working with us, and I still believe the battle would have been just as devastating."
The officials also said that an FBI report, warning that protesters had been preparing for "war", had failed to reach security officials on the eve of the attack.
Former House Sergeant-at-Arms Paul Irving said that despite media reports, "optics played no role in my decision around security".
media captionWatch dramatic new footage of police under attack at the Capitol riot
He denied reports that officials did not want military troops at the Capitol out of concern that it would generate bad publicity.
His account appeared to be in direct conflict with Mr Sund, who testified that Mr Irving had "stated he was concerned about the 'optics' of having National Guard present".
"We all agreed the intelligence did not support" calling in the troops, said former Senate Sergeant-at-Arms Michael Stenger.
Mr Sund added that no civilian police force would have been equipped that day to repel the massive crowd.
Senator Amy Klobuchar, who is leading the hearing, said Pentagon officials will be called next week to testify about the deployment of National Guard troops.
Senators say the hearings will help determine new security measures - including a permanent fence - being considered for the Capitol in the wake of the attack..