See what the FBI has uncovered about the Trump assassination attempt

The FBI said it was investigating the shooting as potential domestic terrorism.

Investigators said on Monday, July 14, that they had obtained access to the cellphone of 20-year-old Thomas Matthew Crooks, who had tried to assassinate former President Donald Trump at campaign rally in Pennsylvania on Saturday, July 13.

This breakthrough allows investigators to analyze the phone’s contents, as the search continues for a motive for the shooting that left one rallygoer dead and two others wounded.

Investigators did not immediately say if the analysis of the phone being conducted at the FBI laboratory in Quantico, Virginia, yielded any clues on what drove the suspect to commit such a brazen attempt on Trump’s life — a key focus of the inquiry.

Officials also said a search of Crooks’ vehicle and home in Bethel Park, Pennsylvania, about 53 miles south of where Saturday’s event occurred, has been done.

This search uncovered two Improvised Explosive Devices (IEDs) in Crooks’ car and one in his home.

“Over the last several months, Crooks received several packages, including some marked as possibly containing hazardous material, according to a review of his shipping history,” the bulletin said.

The bulletin also revealed that on the day of the shooting, Crooks purchased 50 rounds of ammunition before going to the rally in a gun shop in Bethel Park, Pennsylvania. It is unclear what shop the bulletin was referring to.

The agencies warned others who may be inspired to further violence.

“We cannot rule out the possibility that some DVEs or other actors may attempt follow-on or retaliatory acts of violence in response to this assassination attempt,” the bulletin said.

ABC News learned that on the day of the shooting, Crooks told his father he wanted to go to a shooting range and asked if he could borrow his dad’s AR15-style rifle, said a source familiar with the matter. Since the father had occasionally allowed Crooks to go target shooting with the semiautomatic firearm, he didn’t think anything was suspicious when he let him use the rifle again on Saturday, the source said.

Investigators said Crooks used the rifle in the attempted assassination of Trump. The source also said that Crooks recently purchased ammunition online, as well as in person.

Law enforcement has been canvassing local gun shops in the Pittsburgh area for any information they can glean about Crooks’ ammunition buying habits, both purchased in-store and shipped online. Those shops include Allegheny Arms & Gun Works in Bethel Park, roughly a mile from the Crooks’ residence.

“As a responsible member of our community it is our prerogative to cooperate with law enforcement in every way,” Allegheny Arms said in a statement to ABC News. “We are thankful that President Trump was not assassinated and our hearts and prayers go out to all victims of this horrible incident. Out of respect for the ongoing investigation and that of those affected we will not make any further statements.”

FBI investigators have conducted nearly 100 interviews of law enforcement personnel, event attendees and other witnesses as they work to get to the bottom of what transpired at the rally, bureau officials said in a statement.

“The FBI has received hundreds of digital media tips which include photos and videos taken at the scene and we continue to review incoming tips,” the FBI said in its statement.

The FBI is still unable to uncover the motive for the assassination attempt.