(CNN) -- A Puerto Rico Air National Guard WC-130 cargo plane with nine people aboard crashed Wednesday near Savannah, Georgia, military officials said.
A spokesman for the Georgia Air National Guard said the crash was deadly, but no details are being disclosed until investigators have more information about who was on the plane.
"There were airmen on the plane who were deceased, but we're not giving out any numbers at this time," Master Sgt. Roger Parsons of the guard said.
The US Air Force said that an Air National Guard WC-130 from the 156th Airlift Wing in Puerto Rico went down in the area. The 165th Airlift Wing of the Georgia Air National Guard responded to the scene, according to the Air Force. The WC-130 is used for weather reconnaissance, it said.
The aircraft was on a training mission when it crashed not long after takeoff, National Guard officials said.
The plane had been in Savannah for "a number of days" undergoing routine maintenance, said Maj. Paul Dahlen, spokesman for the Puerto Rico National Guard. It was en route to Arizona, he said.
"We don't know the cause of the crash," he said.
A tweet from the Savannah Professional Firefighters Association showed the tail of the plane protruding from thick smoke and fire. State Highway 21 has been shut down, the union said. Another union photo showed debris strewn across the highway, the asphalt a deep black beneath the debris.
The union reported the crash happened in the Savannah suburb of Port Wentworth.
Puerto Rico's governor sent his condolences.
"While we are waiting for more information regarding this unfortunate accident, my thoughts and those of Beatriz are with the families of the crew. They will receive our support and that of the National Guard of Puerto Rico in this process, " Gov. Ricardo Rosselló said.
President Donald Trump tweeted his support.
"Please join me in thoughts and prayers for the victims, their families and the great men and women of the National Guard," he said.
Witness says pilot a hero
Earlier, Georgia National Guard spokeswoman Desiree Bamba said five people were on the plane. The Air Force said five is a standard crew for the WC-130.
Sgt. Noel Velez from the Georgia Air National Guard told CNN that nine people were on board.
Apparently, there were no injuries on the ground.
"As far as we know, no cars were hit, which is an absolute miracle," said Gena Bilbo, spokeswoman for the Effingham County Sheriff's Office.
The Georgia Department of Transportation will need to inspect nearby train tracks for damage, and roadways involved could be closed for weeks, she said. Power has been cut in the area as authorities investigate, she added.
Truck driver Roger Best works for a transportation company in Garden City, about 4 miles south of the crash, and saw the plane overhead before it plummeted to the ground. It was so low when it passed over that it rumbled the ground beneath his rig, he said.
His company handles hazardous materials, he said, expressing gratitude that the aircraft didn't crash in his immediate vicinity.
"If he did this area is a giant bomb and this whole (five-mile) radius would have blown up," he told CNN over Facebook, calling the pilot a hero for avoiding the area. "He barely made it over the tree line (and it) looked as if he tried to turn and nose dive straight into the ground right in front of me."
Christian Freeman saw the WC-130 go down, he said. First, he heard a "loud, strange noise," he said.
"I looked over to my right and seen the plane at very low altitude and making a hard left turn to the ground," he said.
Ten to 15 seconds later, it crashed. It happened so quickly, he didn't have a chance to pull his phone out until after it exploded, Freeman said.
"It was horrible," said Denver Goodwin, who works at a wrecker service down the street from the crash. "The ground shook like a bomb was going off. All the people in the building started panicking. It was absolutely horrible."
Mary Hennessy Cogar was at her place of employment in Garden City and said she felt the impact.
"Our building shook and the lights flickered. We heard a boom of the crash and then a louder boom of the explosion," she said.
Nearby airport affected
The crash occurred a few miles away from the Savannah/Hilton Head International Airport, off state Highway 21, airport spokeswoman Candace Carpenter said.
Shortly after the crash, CNN affiliate WSAV showed video of black smoke and flames billowing from what appeared to be a green hangar or warehouse, but Savannah Fire & Emergency Services said that video was not from Wednesday's crash.
Flights out of the Savannah airport were affected by the crash, according to a tweet from the airport that urged passengers to check the status of their flights before going through security.
Last month, the chairman of the House Armed Services Committee, Rep. Mac Thornberry, released a statement saying the "readiness of the military is at a crisis point" after reports that 16 American service members had been killed in noncombat aircraft crashes over a matter of weeks.
Last summer, the Marine Corps ground its fleet of KC-130T aircraft -- which, like the WC-130, is a variant of the C-130, following a crash that killed 15 Marines and one sailor in Mississippi.
Produced continuously since 1954, the C-130 is a reliable and versatile aircraft with several iterations. It can be outfitted for transport, reconnaissance, search and rescue, research, refueling, patrol or as a gunship.