Law enforcement personnel respond at the scene of a shooting at an Immigration and Customs Enforcement (ICE) field office in Dallas, Texas, U.S., September 24, 2025. REUTERS/Jeffrey McWhorter

By Joseph Ax and Steve Gorman

(Reuters) -The sniper who opened fire on an Immigration and Customs Enforcement field office in Dallas left behind notes saying he acted alone in an attack intended to kill and "terrorize" ICE agents, whose work he viewed as "human trafficking," officials said on Thursday.

Although one person held in ICE custody was killed and two other detainees were critically wounded in Wednesday's bloodshed, it seemed clear from the gunman's writings that "he did not intend to kill detainees or harm them," Nancy Larson, acting U.S. attorney for the Northern District of Texas, said at a news conference.

No federal personnel were injured in the incident.

The perpetrator was found dead from a self-inflicted gunshot wound on the rooftop of a nearby building from which he fired on the ICE building and its driveway with a bolt-action rifle, officials said. The weapon was legally purchased by the gunman in August, according to authorities.

The suspect was identified on Wednesday as Joshua Jahn, 29, a Dallas-area resident who previously attended a community college and had worked as a solar panel installer. He had climbed to his rooftop sniper's perch using a ladder carried to the scene atop his car, Larson said.

His writings were discovered during a search of his home in Fairview, Texas, Larson told reporters.

"Yes, it was just me and my brain," she quoted one of his notes as saying, adding that the messages showed a "game plan" for an attack.

"He hoped his actions would terrorize ICE employees and interfere with their work, which he called human trafficking," the prosecutor said. "What he did is the very definition of terrorism."

Joseph Rothrock, special agent in charge of the FBI field office in Dallas, said the shooter's own words state that he "committed this act alone, and all the evidence we have today would indicate that that's accurate."

"His handwritten notes showed that he did not expect to survive this event," Rothrock said.

TRACKING ICE

Earlier in the day, FBI Director Kash Patel said the suspect had searched for apps in August that track the location of ICE agents and downloaded a list of local U.S. Department of Homeland Security facilities.

Patel also said in a social media post that investigators determined the suspect had researched video of conservative activist Charlie Kirk's highly publicized assassination before carrying out Wednesday's pre-dawn attack in Texas.

Within hours of Wednesday's shooting, the FBI released a photo of an unused bullet found inscribed with the phrase "ANTI-ICE," an early piece of evidence, officials said, that the immigration enforcement agency was the target.

The investigation thus far, Patel said on Thursday, "indicates a high degree of pre-attack planning."

Patel also outlined additional evidence reinforcing the theory that the attack was aimed not at the detainees who were shot but at ICE, the primary enforcement agency of President Donald Trump's aggressive immigration crackdown.

According to Patel, a handwritten note recovered from Jahn's home read: "Hopefully this will give ICE agents real terror, to think, 'Is there a sniper with AP rounds on that roof?'" He did not provide photos or other documentation of the evidence.

Patel also said the suspect had downloaded a document titled "Dallas County Office of Homeland Security & Emergency Management" containing a list of DHS facilities. And during a period of several days in August, the perpetrator had searched apps that tracked the presence of ICE agents.

One of the seriously injured victims is a Mexican citizen, according to Mexico's Foreign Ministry.

Wednesday's attack was the third shooting this year in Texas at a DHS facility. A police officer was shot in July at an ICE detention center in Prairieland, and a Michigan man was shot dead by agents after opening fire on a U.S. Border Patrol station in McAllen in July.

The latest shooting came two weeks after Kirk, co-founder of the conservative student political group Turning Point USA and a close ally of Trump, was shot dead by a rooftop sniper during a speaking event in Utah, fueling fears of a new wave of violence in the United States.

BLAMING ANTI-ICE RHETORIC

Trump and members of his administration immediately blamed left-wing activists for Wednesday's attack, even though there has been no evidence released to suggest the suspect was linked to any outside groups or individuals.

On his Truth Social platform, Trump accused "Radical Left Democrats" of stoking anti-ICE violence by "constantly demonizing Law Enforcement, calling for ICE to be demolished, and comparing ICE Officers to Nazis." He said he would sign an executive order to go after "these domestic terrorism networks."

Reuters reported in August that some ICE officers worried about safety as the Trump administration pushed the agency to dramatically increase arrests.

DHS spokesperson Tricia McLaughlin said in a statement on Thursday that ICE would increase security at facilities across the country.

The administration has defended the work of ICE agents and Border Patrol officers, saying they have been courageous in carrying out their duty to enforce the nation's immigration laws and keep Americans safe.

Democratic politicians and other critics of Trump's immigration enforcement crackdown have accused ICE of creating a climate of fear in heavily Latino communities by deploying militarized patrols of masked agents who emerge from unmarked vehicles to seize people without arrest warrants from day-labor sites, car washes, street vending locations and even schools.

While the administration has portrayed its immigration efforts as targeting criminal offenders, the number of people with no charges or convictions picked up by ICE has risen sharply since Trump took office.

In a joint statement, Democratic leaders in the U.S. House of Representatives condemned the Dallas attack and called for less divisiveness.

Political violence has risen in the United States in recent years, with high-profile attacks targeting figures on both the right and the left, including Trump himself, who endured two assassination attempts during his 2024 presidential campaign.

(Reporting and writing by Joseph Ax; Additional writing and reporting by STeve Gorman; Additional reporting by Ted Hesson and Bhargav Acharya; Editing by Frank McGurty, Nick Zieminski and Diane Craft)