The Federal Bureau of Investigation raided what appeared to be the home of the gunman who tried to assassinate Donald Trump at his Pennsylvania campaign rally Saturday.

According to CBS News ... FBI agents and local law enforcement descended on the Bethel Park residence of now-deceased 20-year-old Thomas Matthew Crooks late last evening. Public records show that a man by the same name and age lived at that location.

During the raid, federal agents closed down streets in the area and neighbors were evacuated from their houses.

CBS said Bethel Park Police launched a bomb investigation at Crooks' home, although it was unclear why or if any explosives were found.

Crooks was fatally shot by Secret Service agents as he attempted to murder the former president at the rally in Butler, PA.

Trump was struck by a bullet in the right ear as he stood at a podium giving a stump speech. He was rushed to a local hospital, where he was treated and released hours later. Three bystanders were also hit by gunfire and one was killed.

TMZ obtained a shocking video of Crooks lying on his belly on a rooftop nearby, firing shots at Trump onstage. FBI officials said they are still trying to determine a motive.