The Secret Service missed multiple opportunities to stop the attempted assassination of then-candidate Donald Trump at a 2024 campaign rally in Butler, Pennsylvania, according to a scathing new Department of Homeland Security inspector general report.

The 64-page report concluded the agency failed to detect, prevent, and disrupt gunman Thomas Crooks before he opened fire on July 13, 2024, citing breakdowns in communications, intelligence sharing, site security and counter-drone operations.

"The Secret Service missed multiple opportunities to detect, prevent, and disrupt" the attack, the IG found, while blaming the failures on poor policies, inadequate coordination and insufficient collaboration with state, and local law enforcement.

Among the report's most striking findings was that the Secret Service failed to receive 102 radio transmissions from local law enforcement warning about Crooks because it never established a joint communications room with officers securing the event.

According to the report, local officers began reporting a suspicious man carrying a rangefinder near the American Glass Research complex well before the shooting.

Later transmissions warned the suspect had climbed onto the roof and was armed with a rifle.

Despite those increasingly urgent warnings, Secret Service personnel received only five phone calls and three text messages about Crooks, meaning Trump's protective detail was never informed of the growing threat before the gunman fired eight shots.

Communications failures prevented agents from alerting Trump's security team as Crooks positioned himself on a rooftop roughly 155 yards from the stage.

The inspector general also found Crooks flew a drone over the rally site for nearly nine minutes hours before the attack.

The flight went undetected because the Secret Service's counter-drone system was inoperable and assigned to a single operator the report described as under-trained.

After learning an armed suspect was on the roof, the counter-drone operator searched online for the building's location rather than asking local officers, the New York Post reported.

The report found the operator was still searching the internet when Crooks opened fire.

Investigators also faulted the Secret Service for failing to secure areas outside the event perimeter, despite receiving plans from Pennsylvania State Police showing the vulnerable location, and for not using available vehicles or other resources to block Crooks' line of sight to the stage.

The report included seven recommendations aimed at strengthening communications, intelligence sharing, and event security.

The Secret Service said it agreed with all of the recommendations, adding that many reforms have already been implemented following the Butler attack.

Crooks was killed by law enforcement moments after the shooting.

One rally attendee was killed, two others were wounded, and Trump survived after a bullet grazed his right ear.

Reuters contributed to this report.