Joseph Rothrock, special agent in charge of the Dallas FBI field office, described the "significant, high-degree of pre-attack planning" that preceded the deadly shooting. Rothrock said Jahn searched for information about the ICE facility and how to track the location of ICE agents.

Police responded to shots fired at the U.S. Immigration and Customs Enforcement office in Dallas about 7 a.m. local time.

Administration officials repeatedly argue political opponents are fueling surge in threats against federal agents

National, state and local leaders condemned the violence and offered prayers after a deadly shooting at a Dallas ICE facility.

Officials still haven't released the identities of the three detainees shot at an ICE facility in Dallas, one fatally.

"This violence is the result of the Radical Left Democrats constantly demonizing Law Enforcement, calling for ICE to be demolished, and comparing ICE Officers to 'Nazis,'" Trump wrote in a social media post on Wednesday, in which he said he had been briefed on the shooting.