A B-1 Lancer bomber assigned to Ellsworth Air Force Base in South Dakota crashed during a training mission Thursday afternoon, according to a news release from the base.

The aircraft was attempting to land on the installation at around 5:50 p.m. when it crashed.

Four crew members were on board during the incident and all four ejected safely, according to the base. Further details on their conditions were not released.

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The base said a board of officers will be investigating what caused the accident.

Automated weather reporting equipment recording airfield conditions reported poor visibility, freezing temperatures and low clouds at the time of the crash, according to The Associated Press.

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The B-1 Lancer bomber is a "highly versatile, multi-mission weapon system," according to the Air Force, and it is "capable of tracking, targeting and engaging moving vehicles as well as self-targeting and terrain-following mode."

The aircraft carries the largest conventional payload of both guided and unguided weapons in the Air Force inventory" and is considered "the backbone of America's long-range bomber force," according to its description on the USAF website.

While 100 were originally built, fewer than 60 remain in service at Dyess Air Force Base in Texas and at Ellsworth, the AP reported.

South African athlete Oscar Pistorius was released from prison on parole on Friday after serving nearly nine years for the shooting death of his girlfriend, Reeva Steenkamp, on Valentine's Day in 2013.

Pistorius, once hailed an inspiration as a double-amputee Olympic runner competing against able-bodied athletes, was serving a 13-year sentence at Atteridgeville Correctional Center in the South African capital of Pretoria.

Little details surrounding his release were available, but the announcement from the country's Department of Corrections came at around 8:30 a.m. local time, according to The Associated Press.

Pistorius was convicted of murder in 2015 and sentenced to 13 years and five months in prison. In South Africa, serious offenders are eligible for parole after serving at least half of their sentence.

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Pistorius was granted parole on Nov. 24 under various conditions, including that he not leave the area of Pretoria where he is set to live without permission from authorities, the Department of Corrections said at the time.

He will also be required to attend a program to deal with his anger issues and will have to perform community service. His parole conditions will be in place for five years.

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Pistorius testified at his murder trial that he killed Steenkamp, 29, by mistake, thinking she was a dangerous intruder hiding in his bathroom in the middle of the night when he fired four times through the door with his licensed 9mm pistol. 

Prosecutors argued that Pistorius killed her in a rage after she had fled to the toilet cubicle during a late-night argument.

Pistorius was initially convicted of culpable homicide, which is comparable to manslaughter, in her death. That conviction was overturned and he was convicted of murder after an appeal by prosecutors. 

They also appealed against an initial sentence of six years for murder, and Pistorius was ultimately sentenced to 13 years and five months in prison.

Fox News Digital reached out to the South Africa Department of Corrections, but did not hear back by time of publication.

Fox News Digital's Michael Dorgan and Rebecca Rosenberg, and The Associated Press contributed to this report.