The man suspected of the shooting at a Dallas Immigration and Customs Enforcement field office on Wednesday opened fire "indiscriminately" from a nearby rooftop, killing one detainee and wounding two others in a van, authorities said.

The shooting suspect was identified as 29-year-old Joshua Jahn, multiple law enforcement sources told ABC News.

Authorities said he took his own life.

Joshua Jahn is seen in a 2016 booking photo. Collin County Sheriff's Office

Here's what we know about the suspect.

Suspect allegedly left behind note about ICE

FBI Director Kash Patel posed that Jahn allegedly left a handwritten note that read, "Hopefully this will give ICE agents real terror, to think, 'is there a sniper with AP rounds on that roof?" -- referring to armor-piercing bullets.

Patel a

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