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.' Dallas police said officers responded to an assist officer call at the facility around 06:40 local time (11:40 GMT). The Department of Homeland Security (DHS) said three detainees were shot. One has died, and two were critically injured, it said. They remain in critical condition, officials later said. The department had initially said two people had died in addition to the shooter, only to revise that information hours later. One injured detainee is a Mexican national, the Mexican foreign ministry said. Acting ICE director Todd Lyons identified the shooter as 29-year-old Joshua Jahn, who died of a self-inflicted gunshot wound, authorities said. Voter records indicate he was registered as an independent and last voted in the general election in 2024. Jahn had cannabis-related charges in Texas dating back to 2016. Jahn's brother, Noah, told NBC that his brother did not seem political. He said he last saw him two weeks ago and nothing seemed out of the ordinary. 'He didn't have strong feelings about ICE as far as I knew,' Noah Jahn said. 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, adding the FBI was investigating it as 'an act of targeted violence.'