Top U.S. House investigators announced on Monday that the attempted assassination of former President Donald Trump on July 13th was entirely “preventable,” according to a preliminary report based on expert and witness testimony regarding multiple security failures that occurred that day.

A breakdown in communication and planning between state and federal agencies revealed significant gaps in the protection provided to Trump during a rally in Butler, Pennsylvania, where a gunman was able to fire a rifle round at him from a nearby rooftop.

Fox News reported on the initial findings from a House Task Force that highlighted alarming failures within the Secret Service.

“Although the findings in this report are preliminary, the information obtained during the first phase of the Task Force’s investigation clearly shows a lack of planning and coordination between the Secret Service and its law enforcement partners before the rally,” the report said.

“Put simply, the evidence obtained by the Task Force to date shows the tragic and shocking events of July 13 were preventable and should not have happened,” the report added.

Task Force Chair Mike Kelly (R-PA) has discreetly issued three subpoenas to local Pennsylvania agencies for “sensitive documents,” according to Politico. These documents are expected to be reviewed and included in a final report set for release this December.

Local authorities have previously disputed claims made by former Secret Service leadership regarding the adequacy of training and preparation, including accountability for securing the rally’s perimeter from which the gunman fired.

The investigation also uncovered that the Secret Service borrowed members of Trump’s detail from other federal agencies, with some receiving only brief webinar training before being deployed in the field.

Shortly before 20-year-old gunman Thomas Matthew Crooks began firing at Trump, grazing his right ear, a breakdown in communication between the Secret Service and other agencies caused “critical pieces of information … [to move] slowly due to fragmented lines of communication and unclear chains of command on July 13,” and the Secret Service “did not effectively verify responsibilities were understood and being executed,” the report says.