How powerful was Denver’s North Capitol Hill three-alarm construction fire that drew hundreds of onlookers gaping nearby and miles away? The blaze melted at least 30 cars, shot flames up to 200 feet in the air and produced heat so intense that it could be detected from space.

An apartment construction site at East 18th Avenue and Emerson Street in the North Capitol Hill neighborhood, also known as Uptown, caught fire just after noon on Wednesday. After nearly 100 firefighters rushed to the scene to douse the flames, authorities determined two people were missing, one construction worker was critically injured, one firefighter suffered minor injuries and four people were treated for smoke inhalation.

Denver Fire Department spokesman Capt. Greg Pixley called the amount of heat the fire produced significant. “We were 300 feet away and could feel the volume of heat.”

Pixley explained that anything producing the amount of heat the fire was emitting creates energy that can cause things nearby to ignite. This is how a building directly south of the construction site caught fire.

A total of six buildings were involved in the fire, with four saved and the original construction site a total loss. Ash and debris caused roof fires on six other buildings nearby.

By Pixley’s count, at least 30 vehicles near the burning building were destroyed. Photos from the Denver Police Department show charred cars appearing as though they had melted into the pavement. Three Denver Fire Department trucks were damaged.

SCENE at 18th and Emerson following fire in the area. Scene remains active and residents are asked to avoids the area and find alternoute routes. #Denver @Denver_Fire pic.twitter.com/oBlILfzADi — Denver Police Dept. (@DenverPolice) March 7, 2018

The National Weather Service in Boulder tweeted a photo showing a satellite view from 22,000 miles in space captured the heat of the blaze.

The Denver construction fire is detectable from space. The GOES-16 satellite loop shows the heat signature from the fire. #cowx pic.twitter.com/HmsxR6jY37 — NWS Boulder (@NWSBoulder) March 7, 2018

Todd Dankers, a meteorologist with the National Weather Service, said using satellites to spot fires isn’t unusual or new, but that better technology within the last year or so has allowed for meteorologists to get better images.

“It’s kind of our new normal now,” Dankers said. “It does point to the capability of monitoring fire outbreaks even in remote areas.”

Bystanders from miles away took to social media, in awe of the huge orange flames and smoke column interrupting the otherwise clear sky.

Pixley compared the exposed wood in the apartment building to kindling in a campfire.

“When you throw wood on a campfire, it’s exposed to the flames immediately and quickly reaches ignition,” he said. “In this case there was nothing to protect the wood. Exposed wood on construction projects can be quite dangerous.”

Kristen Cohen said she was in her home in the 1800 block of Clarkson Street when firetrucks with wailing sirens descended on her neighborhood.

“I went out on my porch and it felt like I was next to the sun,” she said.