Leaders of a House panel on Tuesday called for more transparency from the Secret Service and criticized the agency’s director for being the sole official to testify about an incident earlier this month in which two agents allegedly drove into a White House barricade and disrupted an investigation.

“I’m simply disappointed we will not hear from the other Secret Service witnesses invited here,” said Rep. Elijah Cummings (D-Md.) a ranking member of the House Oversight Committee. “No other committee is doing more on this issue than ours.”

Cummings and committee Chairman Rep. Jason Chaffetz (R-Utah) called on Secret Service Director Joseph Clancy and several other agency officials on the scene of the March 4 incident to testify.

But in a letter to the committee late last week, Clancy, who over the last two weeks has testified before other congressional committees about the incident, said he would be the lone agency official to sit before the committee. While speaking to lawmakers earlier this month, Clancy said he was “very frustrated” that he did not hear about the incident until five days after it occurred and promised to hold his staff accountable pending an internal investigation.

“I don’t think your appearance alone is sufficient for this hearing today,” Chaffetz told Clancy in his remarks. He added, “the Secret Service has refused our request,” to hear from additional witnesses to get a clearer picture of what occurred.

Lawmakers on Tuesday were investigating allegations that two senior Secret Service agents, purportedly under the influence of alcohol, disrupted an investigation on the White House grounds on the night of March 4. One of the agents is a senior official who works in President Barack Obama’s security detail.

Clancy, who was appointed to head the embattled agency in February by Obama, took responsibility for the incident and emphasized to the committee that the agency was investigating it. But he also disputed some reports that agents “crashed” into a barrier, and instead called it a “nudge” by the agents.

In remarks, lawmakers also questioned why some video surveillance of the incident was erased. Lawmakers viewed short video clips of the incident and called for a complete accounting of all video footage associated with the incident.

Clancy on Tuesday said all video will be made available to the committee in the near future as the investigation is ongoing.

The brief video clips viewed by lawmakers shows a Secret Service vehicle entering the White House complex on March 4 and appearing to tap a barreled barrier.

“It was more of a nudge, than a crash . it was more of a purposeful move” Clancy, noting the agents were traveling between 1 and 2 miles per hour, said in testimony.

Still, the fact that some of the video was erased left lawmakers concerned that the Secret Service was not being transparent enough.

“The local Piggly Wiggly, my local supermarket, has 30 days of retained tapes,” said Rep. Stephen Lynch (D-Mass.). “By scrubbing those tapes, not asking questions, it just, coming from an intelligence-gathering organization, it just leaves me almost speechless. I just can’t imagine a more deliberate attempt not to understand the nature of the problem.”

Last fall, then-Secret Service head Julia Pierson resigned under pressure after several high-profile security breaches, including an incident in which a man jumped the White House fence and made it inside the building. In addition to the fence jumper, concern was raised after an armed guard who did not have security clearance was able to ride in an elevator with Obama while he was visiting the Centers for Disease Control and Prevention in Atlanta last year.

Clancy, a seasoned Secret Service veteran, was tapped by Obama to clean up the agency and has implemented several changes since he’s been in charge. Those changes include directing all White House ground personnel to undergo practical training and calls for additional funding for that effort.

At Tuesday’s hearing, Rep. Michael Mulvaney (R-S.C.) alluded to Clancy’s long career at the agency.

“Was it always this bad?” asked Mulvaney about the mishaps that have plagued the Secret Service.

“No, sir,” Clancy said.