The WC-130 plane that killed nine airmen when it slammed into the ground Wednesday in Georgia was manufactured in the late 1970s and reportedly being flown to retirement -- raising questions if the age of the aircraft was a factor in the crash.

The nine airmen, all from the Puerto Rico Air National Guard, were officially pronounced dead Thursday, hours after authorities combed through the wreckage.

The airmen were identified Thursday as Maj. José R. Román Rosado, Maj. Carlos Pérez Serra, 1st Lt. David Albandoz, Senior Master Sgt. Jan Paravisini, Master Sgt. Jean Audriffred, Master Sgt. Mario Braña, Master Sgt. Víctor Colón, Master Sgt. Eric Circuns and Senior Airman Roberto Espada.

Rosado was the pilot of the WC-130 and had served in the National Guard for 18 years before his death. Albandoz was his co-pilot and also had 16 years of service.

Col. Pete Boone, the Vice Commander 165th Airlift Wing of the Air National Guard, said in a Thursday morning news conference that officials had begun notifying victims’ families.

“An investigation is currently in progress to determine the cause of this tragic event and ways to prevent such a [crash] from happening in the future,” Boone said.

Boone said the plane, which was manufactured in the late 1970s, was at the Savannah/Hilton Head International Airport for routine maintenance and was headed to Arizona as part of a routine mission. Boone wouldn’t say what would have happened to the plane after it arrived in Arizona, but Adjutant General Isabelo Rivera told The Associated Press the aircraft was being flown into retirement.

"The planes that we have in Puerto Rico -- it's not news today that they are the oldest planes on inventory" among all National Guard planes nationwide, and they often face delays in getting spare parts shipped to the island, Rivera said.

Surveillance video captured the moment the plane nosedived into the ground, bursting into flames upon impacting a roadway around 11:30 a.m. Wednesday. The plane hit the ground so hard that the only intact part of the aircraft was the tail section. No cars or trains, however, were involved in the crash.

Boone said it’s unclear if the bodies of all nine airmen have been recovered as of Thursday morning.

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. The squadron used the plane to rescue Americans from the British Virgin Islands after Hurricane Irma, and later supplied food and water to Puerto Ricans desperate for help after Hurricane Maria.

"The National Guard is an extended family," Rivera said.

The Associated Press contributed to this report.