The sniper who carried out the shooting at an Immigration and Customs Enforcement field office in Dallas left behind notes indicating that he acted entirely alone in a premeditated attack designed to kill and “terrorise” ICE agents, whom he considered to be engaged in what he described 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 government personnel were injured in the incident, though officials said ICE agents and other federal officers rushed into harm’s way to save some detainees sitting helpless in transport vans while shots were being fired.

The perpetrator was found dead from a self-inflicted gunshot on the rooftop of a nearby building from which he fired on the ICE building and transport vans parked in its entryway 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 the messages showed a “game plan” for the attack.

‘Very Definition Of Terrorism’

“He hoped his actions would terrorise 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 all indications were that the shooter “committed this act alone,” as stated in his own words.

“His handwritten notes show he did not expect to survive this event,” Rothrock said.

President Donald Trump and others in his administration say the incident proves an increase in vitriolic rhetoric directed against ICE, the primary enforcement agency of Trump’s aggressive immigration crackdown, is putting law enforcement at greater risk.

They also cast blame on the availability of apps capable of tracking the location of ICE agents.

“It’s no different than giving a hit man the location of their intended target, and this is exactly what we saw happen in Dallas yesterday,” Marcos Charles, an ICE executive associate director, said at Thursday’s briefing.

According to FBI officials, Jahn used ICE-tracking apps and downloaded a list of local U.S. Department of Homeland Security facilities in preparation for Wednesday’s pre-dawn attack.

The suspect also had researched video of conservative activist Charlie Kirk’s highly publicised assassination, FBI Director Kash Patel said on social media on Thursday. The investigation thus far, Patel said, “indicates a high degree of pre-attack planning.”

One of the first glimmers of the gunman’s motives to be made public was a photo the FBI released within hours of the shooting of an unused bullet found inscribed with the phrase “ANTI-ICE.”

Escalating Violence

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 centre 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.

ICE officers nationwide have been subjected to a 1,000% increase in assaults stoked by “violent rhetoric,” Charles said, “and it has to stop.”

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.

On his Truth Social platform, Trump accused “Radical Left Democrats” of stoking anti-ICE violence by “constantly demonising Law Enforcement, calling for ICE to be demolished, and comparing ICE Officers to Nazis.”

On Thursday, Trump signed a presidential memo seeking to crack down on what he has characterised as organised efforts by left-wing groups to commit or incite political violence.

In the case of Jahn and Wednesday’s shooting, investigators have found “no evidence of membership in any specific group or entity,” Larson said.

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 militarised patrols of masked agents who emerge from unmarked vehicles to seize people without arrest warrants from day-labour 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.

(With inputs from Reuters)