Republican presidential candidate and former U.S. President Donald Trump is whisked away by Secret Service after shots rang out at a campaign rally at Butler Farm Show on July 13 in Butler, Pa. AFP-Yonhap

The Federal Bureau of Investigation has identified 20-year-old Thomas Matthew Crooks as the "subject involved" in the attempted assassination of former President Donald Trump, it said in a statement on Sunday.

Crooks, who was from Bethel Park, Pennsylvania, was registered as a Republican, according to the state's voter records.

The Federal Aviation Administration said on Sunday that the airspace over the Bethel Park was closed "effective immediately" for special security reasons. (Reuters)