A 20-year-old man allegedly tossed a Molotov cocktail at the home of Sam Altman, OpenAI’s chief executive, early on Friday morning, San Francisco police have said.

The suspect, who allegedly threw the explosive at the $27 million North Beach residence at about 4.12am, has been arrested but not identified. The same person allegedly threatened to torch OpenAI’s headquarters in the city. No injuries were reported.

The San Francisco police wrote in a statement on X on Friday morning that the agency responded to a “fire investigation” after the man allegedly threw a Molotov cocktail at Altman’s residence. Law enforcement said there was a “fire to an exterior gate”, after which the suspect fled on foot.

About an hour later, just after 5am, police responded to reports from a business in the Mission Bay neighbourhood, where OpenAI’s headquarters are located, about a man “threatening to burn down the building”. Officers said they recognised the man as the suspect from the earlier incident and detained him.

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OpenAI, best known for making the ChatGPT chatbot, confirmed the incident in a statement.

“Early this morning, someone threw a Molotov cocktail at Sam Altman’s home and also made threats at our San Francisco headquarters. Thankfully, no one was hurt,” a representative said. “The individual is in custody, and we’re assisting law enforcement with their investigation.”

OpenAI sent a note informing employees Friday morning about the incident, and told them there was no immediate threat to them or other offices. The note also mentioned there would be increased police and security presence around its Mission Bay offices.

Last year OpenAI locked down its San Francisco office after the company reported a threat from a person once affiliated with an anti-AI activist group. – Guardian service