Federal prosecutors said the group planned to assassinate U.S. President Donald Trump, Vice President JD Vance, Israeli Prime Minister Benjamin Netanyahu, billionaire Elon Musk and other senior officials during the event.
According to the indictment, all eight defendants were charged in two separate conspiracies: one to provide material support to terrorists and another to commit murder on federal property and assassinate a federal official.
Investigators said the group began preparing for the attack in May, stockpiling cash, firearms, ammunition, body armor, explosives, drones, medical supplies, communications equipment and other materials.
Law enforcement officials became aware of the potential threat on June 10, four days before the planned event.
Authorities said the suspects subscribed to fringe conspiracy theories and believed the attack would destabilize the U.S. government.
One of the suspects told investigators the group planned to fly explosive-laden drones into the event before opening fire on the crowd as people fled.
Investigators also said the suspects communicated through online chats and forums, organizing members into different tiers. The group also conducted firearms and tactical training.
The suspects face life imprisonment if convicted.
On June 14, the White House hosted a UFC event as part of celebrations marking the 250th anniversary of the United States, which coincided with Trump's 80th birthday. About 100,000 people attended the event.
Trump's initiative required 19 months of planning and several weeks of construction. The estimated $60 million cost was covered by the UFC, while the federal government was responsible for "emergency medical services, law enforcement and security," according to White House Director of Administration and Management Joshua Fisher.