SAN FRANCISCO (KRON) — A San Francisco City Supervisor who last week voted to authorize the San Francisco Police Department to use killer robots has reversed course and now opposes the measure. In a Twitter threat, SF District 4 Supervisor Gordon Mar said he regrets his initial “yes” vote and “will vote no tomorrow.”

“I’m grateful to all who’ve expressed concerns with our vote authorizing SFPD to use robots to kill suspects in extreme circumstances,” Mar tweeted. “Despite my own deep concerns with the policy, I voted for it after additional guardrails were added.”

“I regret it. I will vote no tomorrow,” he added.

The SF Board of Supervisors voted 8-3 in favor of authorizing use of the robots last week. The robots would be armed with explosives and could be deployed, theoretically, in extreme situations where lives are at stake and no other alternative is available.

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The “yes” vote from the SF board follows a similar proposal being shot down across the Bay in Oakland. The passage of the authorization in SF has raised eyebrows as many were surprised that a city with a reputation for leaning left would approve such a measure. The vote has sparked debate around the ethics of using robots to kill suspects from a distance.

“Even with additional guardrails, I’ve grown increasingly uncomfortable with our vote and the precedent it sets for other cities without as strong a commitment to police accountability,” Mar tweeted. “I do not think making state violence more remote, distanced, and less human is a step forward.”

The SF Board of Supervisors is set to take a second vote on the issues on Tuesday. On Monday, protesters gathered on the steps of City Hall to oppose the measure.

The Associated Press contributed to this report.