The 604-ton Falcon 9 rocket was being fueled with a potent mix of liquid oxygen and rocket-grade kerosene propellant when an explosion quickly enveloped the launch pad in flames.
The ensuing fireball delivered a blow to the efforts of two high-profile billionaires: SpaceX Chief Executive Elon Musk and Facebook's Mark Zuckerberg.
The rocket, scheduled to launch Saturday, was carrying a satellite designed to bring the Internet to remote villages in Africa and help the social media giant expand its global footprint.
Instead, the satellite and rocket were destroyed in several fiery explosions — loud enough to be heard 40 miles away — as wind spread a plume of black smoke so large and thick it showed up on weather radar.
"We heard what sounded like a huge thunder strike," said Evan Zimny, 23, who works about five miles away in an office building that shuddered from the blast as ceiling tiles fell.
"The building and window shook rapidly and loudly and [that] lasted a couple of seconds," he said.
There were no reported injuries.
Musk said the explosion took place as the rocket was being fueled for a test ahead of a planned weekend launch. The cause was not immediately known, he said.
But even as the smoke was clearing, the ramifications started to become apparent.
They stretched from SpaceX's Hawthorne headquarters to aerospace companies in Israel to rural Africa.
In recent years, the commercial space industry has grown in size and importance. Last year, SpaceX received approval from the Air Force to compete for Pentagon contracts, pitting the firm against United Launch Alliance, a joint venture of Boeing Co. and Lockheed Martin Corp. that had long enjoyed a monopoly on national security launches.
Several other private companies — including Jeff Bezos' Blue Origin and Richard Branson's Virgin Galactic — are also racing to launch satellites and tourists into orbit.
"Today's SpaceX incident — while not a NASA launch — reminds us that spaceflight is challenging," NASA tweeted. "Our partners learn from each success & setback."
Industry analysts said the explosion could delay space launches. Saturday's planned liftoff would have been the ninth by SpaceX in 2016, with eight more planned by the end of the year.
"It's clear there will be some sort of delay," said Phil Smith, senior space analyst at the Tauri Group.
The explosion — the second Falcon 9 failure in 14 months for SpaceX — could also be a setback to Musk's efforts to prove that his company can quickly and safely launch and reuse rockets. Just this week, SpaceX had announced that it had signed its first customer to launch a satellite with a reused booster.
SpaceX, whose full name is Space Exploration Technologies Corp., charges at least $62 million for each launch. This spring, the company landed its first big Pentagon job — an $83-million contract from the Air Force to launch a global positioning system satellite from Cape Canaveral in 2018.
Uzi Rubin, former chief of Israel's missile defense program, said that rocket launches are never foolproof. But major mishaps usually don't happen during launch preparations, he said.
"The Falcon 9 up till now was very reliable," Rubin said. "There's always a chance of failure, but usually it happens after the launch. This time it happened on the launch pad."
In the long run, however, analysts said there would be few impacts on the burgeoning launch and small satellite industries, as well as on SpaceX.
Bill Ostrove, aerospace and defense analyst at market research firm Forecast International, pointed to SpaceX's 93% launch success rate, which is "right in the ballpark" of the industry's average of 95%.
"Considering they do have a decent success rate, I don't see much harm being done to the industry as a whole," he said.
Still, the explosion was another blow to Musk, the Los Angeles entrepreneur who also runs Tesla Motors Inc. He began his summer by learning that federal regulators were investigating the Autopilot feature of the Tesla Model S electric car after a fatal crash.
And SpaceX was still trying to ramp back up after another Falcon 9 rocket exploded in midair minutes after liftoff from Cape Canaveral Air Force Station in June 2015. Lost in the blast was $110 million in cargo for the International Space Station.
After an investigation of that incident, Musk said that the company believed the rocket disintegrated after a small steel band purchased from a subcontractor snapped under pressure.
The explosion caused SpaceX to reduce its launches last year to only six.
Another billionaire's ambitions also took a hit Thursday.
The Amos-6 satellite sitting atop the SpaceX rocket was going to beam high-speed Internet and other digital services to sub-Saharan Africa, the Middle East and parts of Europe as part of an effort by Facebook to provide Internet access to poorly connected areas.
"I'm deeply disappointed to hear that SpaceX's launch failure destroyed our satellite that would have provided connectivity to so many entrepreneurs and everyone else across the continent," Zuckerberg, who was in Africa, said in a Facebook post.
It was the first attempt by the company's Internet.org initiative to deliver Internet signals from space. But Zuckerberg said Facebook was working on other technologies, such as an unmanned solar-powered plane that can transmit the Internet to remote locations.
"We remain committed to our mission of connecting everyone, and we will keep working until everyone has the opportunities this satellite would have provided," he said.
The Amos-6 satellite was a total loss, said Space Communication, the Tel Aviv company that was going to operate it. Known as Spacecom, the company had contracts with the Israeli government to use the satellite, which was meant for broadcast and telecommunications, as well as with Facebook.
Spacecom's stock fell nearly 9% in trading in Tel Aviv on Thursday.
The satellite's manufacturer, Israel Aerospace Industries, took out an insurance policy on the Amos-6 worth $285 million – the same amount as the total value of the satellite, according to a person familiar with the matter.
That policy, also known as a marine cargo insurance policy, covers transit and pre-launch processing of the satellite from the factory to the launch site. Spacecom's insurance policy doesn't cover risk of loss until the launch.
Special correspondent Joshua Mitnick in Tel Aviv and Orlando Sentinel reporter Marco Santana contributed to this report.
4:20 p.m.: This article was updated with additional details.
7:37 a.m.: This article was updated with confirmation from SpaceX.
7:10 a.m.: This article was updated with additional details.