PORT WENTWORTH, Ga. -- An Air National Guard C-130 cargo plane crashed Wednesday onto a busy highway moments after taking off from a Georgia airport, killing nine National Guard members from Puerto Rico, authorities said. The top official of the Puerto Rico Air National Guard, Adjutant Gen. Isabelo Rivero confirmed there were no survivors. The plane narrowly missed people on the ground.

Black smoke rose into the sky after the plane crashed into a median on the road outside Savannah, Georgia, around 11:30 a.m. local time. Firefighters later put out the blaze.

A driver on a nearby road saw the plane plummet to the ground, CBS News correspondent Laura Podesta reports.

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"Right when it came over a set of trees there, I saw it do a roll upside down," Jimmy Livingston said. "When it rolled upside down, it did a complete straight turn into the ground."

An aerial view shows the crash site in Georgia on Wed., May 2, 2018. WGCL-TV

CBS News correspondent Mark Strassmann reports that this particular C-130 was one of the oldest still flying. The pilot was heading to Tucson, Arizona, to retire the aircraft. After take off earlier Wednesday, it was in the air for about two miles before it crashed.

The one involved in Wednesday's crash was more than 60 years old.

"The planes that we have in Puerto Rico -- it's not news today that they are the oldest planes on inventory" of all National Guard planes nationwide, Rivera said. Puerto Rico's National Guard has five other similar planes, two of which need maintenance and aren't being used, he said.

It's too early to say what might have caused the accident, he said. The plane last received maintenance at the base in Savannah in April.

All nine crew members had helped with hurricane recovery efforts as part of the 198th Fighter Squadron, nicknamed the Bucaneros, which flies out of Base Muniz in the northern coastal city of Carolina, Rivera said.

"This pains us," Rivera said of the deaths. They aren't releasing names until all the families have been contacted, but "most of them already know and have come to the base."

Rivero said in a Wednesday evening press conference that the C-130 has been used in the past to rescue U.S. citizens stranded in the British Virgin Islands following Hurricane Irma and to ferry supplies to the territory of Puerto Rico after Hurricane Maria last year.

The huge plane's fuselage appeared to have struck the median, and pieces of its 132-foot wingspan were scattered across lanes in both directions. The only part still intact was the tail section, said Chris Hanks, a spokesman for the Savannah Professional Firefighters Association.

"It miraculously did not hit any cars, any homes," Effingham County Sheriff's spokeswoman Gena Bilbo said. "This is a very busy roadway."

Eight hours after the crash, she added: "To our knowledge there are no survivors."

The military plane crash site is seen in Savannah, Georgia, on May 2, 2018, in this picture obtained from social media. Twitter/@IAFF574/via Reuters

Senior Master Sgt. Roger Parsons of the Georgia Air National Guard told reporters the cause of the crash was unknown and authorities were still working to make the crash site safe for investigators.

"Any information about what caused this or any facts about the aircraft will come out in the investigation," he said.

The plane had just taken off from the Savannah/Hilton Head International Airport when it crashed, Parsons said.

The Air Force said the plane belonged to the 156th Air Wing out of Puerto Rico, and Puerto Rico National Guard spokesman Maj. Paul Dahlen told The Associated Press that all those aboard were Puerto Ricans who had recently left the U.S. territory for a training mission on the U.S. mainland.

Surveillance video obtained by CBS News from Meadowbrook Leasing LLC shows the plane falling from the sky.

C-130 caught on video (red circle) moments before it crashed in Ga., on Wed., May 2, 2018. Meadowbrook Leasing LLC

Dahlen said initial information indicated there were five to nine people aboard the plane, which was heading to Arizona. He did not have details on the mission.

"We are saddened by the plane accident that occurred today in Georgia," Puerto Rico Gov. Ricardo Rossello said in a tweet. "Our prayers are with the families of the Puerto Rican crew."

President Trump tweeted that he had been briefed on the crash, sending "thoughts and prayers for the victims, their families and the great men and women of the National Guard."

I have been briefed on the U.S. C-130 “Hercules” cargo plane from the Puerto Rico National Guard that crashed near Savannah Hilton Head International Airport. Please join me in thoughts and prayers for the victims, their families and the great men and women of the National Guard. — Donald J. Trump (@realDonaldTrump) May 2, 2018

The plane crashed onto state highway Georgia 21, about a mile from the airport, said Gena Bilbo, a spokeswoman for the Effingham County Sherriff's Office.

"It miraculously did not hit any cars, any homes," Bilbo said. "This is a very busy roadway."

The crash caused a big orange and black fireball and scattered debris over a large area, Bilbo said.

Motorist Mark Jones told the Savannah Morning News that he saw the plane hit the ground right in front of him.

"It didn't look like it nosedived, but it almost looked like it stalled and just went almost flat right there in the middle of the highway," Jones said, describing how people stopped and got out of their cars following the explosion.

"I'm still shook up and shaking. My stomach is in knots because I know they're people just like me. I wasn't that far from it and I could have just kept going and it would have been me and we wouldn't be talking right now," Jones said.

A photo tweeted by the Savannah Professional Firefighters Association shows the tail end of a plane and a field of flames and black smoke as an ambulance stood nearby.

Military c130 down at 21 and Gulfstream Rd. Avoid the area. 21 shut down until further notice. pic.twitter.com/6hUqwmkNUu — IAFF574 Savannah (@IAFF574) May 2, 2018

Savannah's Air National Guard base has been heavily involved in hurricane recovery efforts in Puerto Rico. In September 2017, it was designated by the Air National Guard as the hub of operations to the island in the aftermath of hurricanes Irma and Maria, the base announced at the time.

By early afternoon, Savannah/Hilton Head International Airport said on social media that flights were arriving and departing with minimal delays. It advised motorists that they may need to seek an alternate route to the airport.