At least three hecklers briefly interrupted Salesforce founder and co-CEO Marc Benioff's keynote speech at the opening of the Dreamforce megaconference in San Francisco Tuesday, criticizing a company contract with U.S. Customs and Border Protection.

As Benioff thanked attendees for helping build Salesforce into a CRM juggernaut, an audience member began to criticize the Salesforce contract. At one point, the phrase "Drop the contract" could be heard.

“We are going to let you talk for 30 seconds," Benioff told the heckler, "but at the end of the 30 seconds you have to agree to leave."

On cue, a 30-second timer was displayed on four massive screens. The heckler wasn’t given a microphone, and what was said couldn’t be heard by most of the 10,000 people who packed the room.

When the clock struck zero, Benioff spoke once more: “Now you must leave."

“I let that person speak because I value free speech in this country," he added, drawing applause from the audience. "I value speech of all of the voices to be included.”

After the first heckler left, two others began shouting, but were led away by security, whose presence was increased for the rest of Benioff's hour-long presentation, which was accompanied by slides detailing the company's year-over-year growth in its CRM business.

Salesforce has faced criticism from outside and inside the company for its March 2018 contract with U.S. Customs and Border Protection. In June, 2018, hundreds of Salesforce employees called for the company to end the contract because of the agency’s role in enforcing the Trump Administration's family separation border policy.

After Benioff's speech, a Salesforce spokesperson said the technology is used only for "recruitment, to manage border activities and digital engagement with citizens," adding, "We value free speech and respect the right to peaceful protest."

Prior to Benioff's speech, the opening presentation saluted women, military veterans, touched on gender equality and sustainability.

Dreamforce is the company’s annual mega-conference that attracts 170,000 people and an additional 13 million people who stream the event online.