DALLAS () Federal investigators are seeking a motive after a lethal shooting occurred on Wednesday at a U.S. Immigration and Customs Enforcement field office in Dallas, resulting in the death of one detainee, two others critically injured, and the gunman deceased.

At the facility, one detainee was killed and declared dead at the scene, according to a Homeland Security spokesperson. Two additional detainees sustained critical injuries. DHS reported that the victims were shot in a transport van parked in the facility’s sallyport. No ICE personnel were harmed.

Sources confirmed that the alleged shooter is 29-year-old Joshua Jahn from Collin County, Texas, located north of Dallas, who reportedly committed suicide.

The Department of Homeland Security stated that Jahn commenced firing from a rooftop approximately 450 feet away. Officials indicated Jahn was “indiscriminately” shooting, striking both the ICE office and van during the transfer processing of detainees.

FBI Director Kash Patel posted a photo on social media showing a bullet recovered at the scene with “ANTI-ICE” written on it.

FBI: ‘High degree of planning’ before attack

The FBI also found evidence that demonstrated a high level of planning ahead of the attack.

A handwritten note discovered at his home read, “Hopefully this will give ICE agents real terror, to think, ‘is there a sniper with (armor-piercing) rounds on that roof?” 

Agents are actively working to seize devices, analyze data, and review writings obtained on-site and discovered on the gunman, at his residence, and in his bedroom.

FBI investigates shooting as a targeted act

Homeland Security Secretary Kristi Noem ordered more security at ICE facilities across the U.S., according to a post by the DHS on social media.

Authorities say the ICE field office was riddled with bullet holes, with one round piercing an American flag on display. The FBI said it was investigating the shooting as “an act of targeted violence.”

Officials have not yet released the names of the victims. Jahn, who had a criminal record including drug-related charges, used a bolt-action rifle in the attack, according to a law enforcement official who spoke on condition of anonymity to the Associated Press.

Former Border Patrol agent Ammon Blair told “Morning in America” on Thursday that attacks like this are often carefully planned, adding that investigators have been monitoring a faction within Antifa known as “CrimethInc.” According to Blair, the group’s goal is to create enough fear that ICE officers hesitate to carry out their duties.

“They have a seven-state plan to stop all ICE operations, and they’ve had it for about five years,” he said. “They want to make it so ICE officers hesitate to do their operations due to the threat of violence and nonprotection.”

ICE doing its job, shouldn’t be attacked: EX-FBI agent

The shooting marks the third incident targeting an ICE facility in Texas since July.

Former FBI agent Dennis Franks told ” Live” that ICE agents and officers are simply doing their jobs.

“They want to serve the public and protect the people,” he said, adding, “They shouldn’t be villainized; they shouldn’t be attacked.”

Lawmakers call for an end to political violence

Lawmakers from both parties condemned the violence and emphasized the importance of maintaining civil discourse.

“It is a punch in the gut because time and time again, we are seeing more and more of this violence,” said Rep. Tony Gonzales, R-Texas. “ICE agents are just doing their job — they are not making policy, they are implementing policy. Whether you agree with it or not; they are not the ones who should be to blame.”

Texas Rep. Nicole Collier, D-Fort Worth, cautioned against rushing to conclusions.

“When we are talking about what happened, we don’t know what happened, and so to try and place blame is premature,” she said.

President Donald Trump weighed in on Truth Social, writing, “The brave men and women of ICE are just trying to do their jobs and remove the ‘worst of the worst’ criminals from our country, but they are facing an unprecedented increase in threats, violence, and attacks by deranged radical leftists.”

DHS announced Thursday that ICE has received more than 150,000 applications, and ICE has extended more than 18,000 tentative job offers.