(NEXSTAR) – An unspent casing found while investigating a shooting at a U.S. Immigration and Customs Enforcement facility in Dallas on Wednesday had the message “ANTI-ICE” written on it, FBI Director Kash Patel said.

Three people were shot at the ICE facility Wednesday in what officials believed to be a targeted attack. Two people have died, and a third was in critical condition at the hospital, the Department of Homeland Security said. All three people hit were detainees, according to DHS.

The shooter was also dead from a self-inflicted gunshot wound.

Sharing a photo of the bullets on X, Patel said, “While the investigation is ongoing, an initial review of the evidence shows an idealogical [sic] motive behind this attack.”

No ICE agents were injured in the shooting.

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

The rounds were found near the suspected shooter, said Joe Rothrock, special agent in charge of the Dallas field office, in a press conference.

Officers responded to a call to assist an officer on North Stemmons Freeway around 6:40 a.m. Wednesday, and the preliminary investigation determined that a person opened fire at a government building from an adjacent building.

The attack is the latest public, targeted killing in the U.S. and comes two weeks after conservative leader Charlie Kirk was killed by a rifle-wielding shooter on a roof.

The Associated Press contributed to this report.