One person was killed and two were wounded in a shooting at a US Immigration and Customs Enforcement (ICE) facility in the US city of Dallas on Wednesday, officials said.

The gunman, who opened fire on the ICE field office from the roof of an adjacent building, died of a self-inflicted gunshot wound, they said.

FBI special agent Joe Rothrock told a press conference that the shooting was being investigated as an "act of targeted violence."

"Early evidence that we've seen from rounds that were found near the suspected shooter contain messages that are anti-ICE in nature," Rothrock said.

ICE is the government agency chiefly responsible for carrying out President Donald Trump's controversial campaign pledge to expel millions of undocumented migrants from the United States.

FBI Director Kash Patel published a photo on X of five unspent bullets -- one of which was marked with the words "ANTI-ICE" -- and denounced what he called "despicable, politically motivated attacks against law enforcement."

Rothrock declined to confirm press reports that the three people who were shot were detainees but said "no members of law enforcement were hurt."

The ICE facility which came under attack processes detainees before they are transferred to a long-term detention center, according to US media reports.

Homeland Security Secretary Kristi Noem and Vice President JD Vance condemned violence directed at ICE.

"ICE law enforcement is facing unprecedented violence against them," Noem said on X. "It must stop."

"The obsessive attack on law enforcement, particularly ICE, must stop," Vice President JD Vance said on the social media platform.

After ICE immigration raids in Los Angeles spurred unrest and protests earlier this year, Trump dispatched the National Guard and US Marines to the California city.

Another ICE facility in Texas was the target of an attack in July that left a police officer wounded in the neck.

Ten people have been charged for their roles in the attack on the ICE center in the town of Alvarado.

According to a criminal complaint, the assailants, dressed in black military-style clothing, shot fireworks at the ICE facility and spray-painted "Traitor" and "ICE Pig" on cars and a guard structure.

The Alvarado incident came just days before a man armed with an assault rifle opened fire at a US Border Patrol facility in McAllen, Texas.

The 27-year-old man fired dozens of rounds from an assault rifle at the entrance of the Border Patrol annex before being shot dead.

Two police officers and a Border Patrol employee were injured.

ICE's role in the Trump crackdown has sparked widespread criticism over the organization's use of heavily armed, masked agents to conduct raids in public places against suspected illegal migrants.