Artificial intelligence experts, including Tesla’s Elon Musk, have spoken out against the development of autonomous robots with the power to kill.

There’s already evidence that major technology companies are losing control of the ways that bad people can use their products, technology investor Roger McNamee told CNBC’s “Squawk Alley” on Monday.

“I think what Elon’s talking about here is that once you start applying automated technology to weaponry, horrific things are likely,” McNamee said. “And I suspect that that is true. The point I would make is that I think bad things are already happening.”

Musk was among the signatories of an open letter to the United Nations Convention on Certain Conventional Weapons. The letter warns against autonomous weapons that could be used for terror, by despots, or hacked to kill people at a larger and faster scale than ever.

The letter comes on the heels of terror attacks in Barcelona last week, and a deadly attack at a rally in Charlottesville, Virginia. Both were carried out, in part, by driving cars into a crowd.

“Think about this with automobiles. We never thought of automobiles as terrorist weapons. But once you start applying them that way, they’re really terrifying,” McNamee said. “And I think that’s the issue…. it’s going to be super hard to control how bad people use that technology once it’s developed. Bad people are unlikely to observe the rules. There’s a lot of history suggesting that fear is legitimate.”

McNamee is managing director at Elevation Partners, a firm that has invested in companies like Yelp and Facebook. But McNamee recently said he regrets the effects that Facebook and Google have had on society.

“Those companies, in many ways, have lost control,” McNamee said. “And that a lot of really difficult, bad things are going on in terms of addiction, in terms of what happens in our election and Brexit. You look at these things and you say to yourself, ‘It’s really time for the country to step back and have a conversation about: What is the appropriate role of technology? What are the limits to what we’re going to allow people to do? And how are we going to make sure that society — jobs, people, and livelihoods — are protected?'”

McNamee agrees with Musk and other scientists that it will be difficult to relegate robots to shooting only at other robots. McNamee also urged Musk and other technology leaders to extend their activism to technologies that are doing harm “here and now.” Facebook, Tesla and Google were not immediately available to comment on McNamee’s comments.

“We have in this country had, at least for the last 10 or 15 years, an almost irrational belief that technology always winds up doing good,” McNamee said. “And the reality is, it’s a lot easier to do bad things with technology than it is to do good. To do good takes tremendous discipline and effort over long periods of time. And you can do bad more or less overnight.”