WASHINGTON, D.C. — Former U.S. Secret Service Agent Bill Gage said the Secret Service's protective model prevented a would-be attacker from entering the ballroom at a National Special Security Event held at a Washington, D.C., hotel. No one was killed in the attack, and the attacker did not make it into the ballroom.

"The Secret Service protective model worked here," Gage said. He was a Secret Service special agent for 12 years and served as a counter-assault team leader. He is now the executive protection director for the SafeHaven Security Group.

The attacker breached the outer perimeter and passed through the magnetometer checkpoint before agents at that checkpoint engaged him. Agents were stationed at the door and just inside the event entrance. The Secret Service uses overlapping concentric security rings, including inner, middle, and outer perimeters, designed so that if one perimeter fails, another can stop an attacker.

The White House said the security protocols worked. "This was a massive security success story," Acting Attorney General Todd Blanche said.

Video footage shows senior government members hiding under tables and motioning for their protective detail to assist them. After each incident, the Secret Service studies political assassinations worldwide to improve its protective model, and its training includes in-depth study of political assassinations.

The event has been held at the same hotel for 60 years. The hotel is in a major U.S. city on a busy street and remains operational during the event. National Special Security Events are designated through joint agreement between Congress and the Secretary of Homeland Security. NSSE designation involves its own budget procedure, and the process has been in place since September 11 under U.S. Code.