Notes written by the person who opened fire on an immigration facility in Texas indicate he was targeting ICE agents and did not intend to harm detainees, officials said.


One detainee was killed and two others critically injured after a suspected sniper opened fire at an Immigration and Customs Enforcement (ICE) centre in Dallas on Wednesday.


The suspected gunman died of a self-inflicted gunshot wound, law enforcement officials said.


Speaking at a news conference on Thursday, acting US attorney for the Northern district of Texas, Nancy Larson, identified the shooter as 29-year-old Joshua Jahn, of Fairview, Texas.


Notes found at the shooter's home show he intended to maximise lethality against ICE personnel and to maximise property damage at the facility, she said.


He hoped to minimise any collateral damage or injury to the detainees and any other innocent people, she added.


It seems that he did not intend to kill the detainees or harm them. It is clear from these notes that he was targeting ICE agents and ICE personnel. The victims have not yet been identified.


But Mexico's foreign ministry has said one injured detainee is a Mexican national. Officials had previously said that no law enforcement officers were injured or killed during the incident.


FBI director Kash Patel said in a post on social media earlier that evidence to this point indicates a high degree of pre-attack planning.


Patel said one of the handwritten notes found said: Hopefully this will give ICE agents real terror, to think, 'is there a sniper with AP rounds on that roof?


At the news conference on Thursday, Larson said the shooter very likely acted alone and described the attack as the very definition of terrorism. She emphasized the need to cease the violent rhetoric against ICE personnel.


In the aftermath of the shooting, officials are continuing to investigate Jahn's motives and whether he had any ties to specific extremist groups. The investigation remains ongoing as authorities seek a clearer picture of the intentions behind this targeted ambush-style attack.