A detainee has died and two others are critically injured after a rooftop sniper opened fire at an Immigration and Customs Enforcement (ICE) centre in Dallas, Texas, officials say.

The gunman fired indiscriminately at the ICE facility and at a nearby unmarked van, law enforcement officials say, before dying from a self-inflicted gunshot wound.

No law enforcement were injured. FBI Director Kash Patel posted a photo on X of unused ammunition recovered from the scene. One casing has the phrase “ANTI-ICE” on it.

It is the latest in a string of attacks on ICE facilities in recent months as the agency ramps up efforts to deliver on US President Donald Trump’s pledge for mass deportations.

“While the investigation is ongoing, an initial review of the evidence shows an ideological motive behind this attack,” Patel wrote on X.

“These despicable, politically motivated attacks against law enforcement are not a one-off.”

Acting ICE director Todd Lyons identified the deceased shooter as 29-year-old Joshua Jahn, the BBC’s US partner, CBS News reported.

The Department of Homeland Security (DHS) said three detainees were shot. One has died, and two are critically injured, it said.

The department had initially said two people had died in addition to the shooter, only to retract the statement, republish it, and then correct it again hours later.

FBI special agent Joe Rothrock told a news conference that rounds found near the gunman contained “messages that are anti-ICE in nature”.

“This is just the most recent example of this type of attack,” he said. He said the FBI was investigating it as “an act of targeted violence”.

Dallas police said a preliminary investigation determined the suspect had opened fire from an adjacent building.

“The shooter fired indiscriminately at the ICE building, including at a van in the sallyport where the victims were shot,” DHS said in a statement.

Reuters news agency reported that the building targeted is an ICE field office used for short-term processing of recently arrested detainees, and is not used as a detention facility.

Acting director of the Dallas ICE office Joshua Johnson told the news conference it was the second time he has had to stand in front of the media and talk about a gunman at one of his facilities.

“The takeaway from all of this is that the rhetoric has to stop,” he said.

Texas Senator Ted Cruz also spoke at the news conference, condemning “politically motivated violence”.

“Your political opponents are not Nazis,” he said, urging people not to demonise each other for partisan reasons. “The divisive rhetoric, tragically, has real consequences.”

Homeland Security Secretary Kristi Noem said in a statement: “This shooting must serve as a wake-up call to the far-left that their rhetoric about ICE has consequences.

“Comparing ICE Day-in and day-out to the Nazi Gestapo, the Secret Police, and slave patrols has consequences.”

Republican Governor of Texas Greg Abbott said on X the shooting would “NOT slow our arrest, detention, & deportation of illegal immigrants”.

The ICE field office in Dallas has been targeted by a series of protests this summer.

A man was arrested in August after he entered the facility claiming to have a bomb in his backpack, according to the DHS.

The 36-year-old US citizen, Bratton Dean Wilkinson, had shown the building’s security staff a device on his wrist that he described as a bomb “detonator,” the DHS said.

Last month shots were fired at ICE offices in San Antonio, Texas. No injuries were reported in that incident, which ICE blamed on “political rhetoric”.

Another shooting occurred on the 4 July public holiday at an ICE facility in Alvarado, Texas, after a protest escalated into a face-off with police. An officer was shot in the neck, and survived. Eleven people have been charged over that attack.