Three employees of electric car maker Tesla were tragically killed after their light plane crashed into an electricity transmission tower in California.
The crash caused a 10-hour blackout in Palo Alto, home to some of the world's largest technology companies.
Tesla chief Elon Musk confirmed the tragedy in a statement.
"Three Tesla employees were on board a plane that crashed in East Palo Alto early [yesterday] morning," Musk said.
"We are withholding their identities as we work with the relevant authorities to notify the families. Our thoughts and prayers are with them.
"Tesla is a small, tightly-knit company, and this is a tragic day for us."
The Mercury newspaper reported the Cessna 310 crashed just after take-off in foggy conditions. One of those killed was reported to be an engineer at Tesla.
Facebook and VMware were among the Palo Alto-based companies to tweet business statuses during the power outage.
"It's one of those days at the office: The power is out in our home of Palo Alto, but we're working and Facebook will be available as normal," Facebook said.
VMware's phone system for customer support was down for 10 hours.
"Phones are NOT working. No ETA at this time," the virtualisation software firm tweeted. Ten hours later it tweeted: "Happy to share that all network operations are up and running. Power has been restored - back to business as usual."