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.

Here's what we know about the suspect.

There is no word yet on a possible motive.

However, FBI officials said rounds found near the suspect contained "messages that are anti-ICE in nature."

FBI Director Kash Patel released an image of recovered shell casings, including one that had been engraved with the phrase "ANTI ICE," he said.

While no officers were injured, the Department of Homeland Security said the shooting was "an attack on ICE law enforcement."

A spokesperson for the University of Texas – Dallas said that a person matching Jahn’s name and date of birth had "briefly attended" the university "over a decade ago."

Two childhood friends told ABC News they had not seen Jahn in around 10 years, but remembered him as mainly interested in video games and internet culture.

Both friends asked not to be named due to concerns about potential harassment.

"This is a complete shock to me," one of the friends told ABC News. "Josh was the least political out of all the people I knew in high school. He liked playing video games,” one of the friends."

Both friends provided a username that they said belonged to Jahn on the gaming website Steam, which is also linked to a Reddit account.

The Reddit account has not been used in around six years. Previous posts point to an interest in gaming and smoking marijuana.

In addition to the Reddit account, the Steam profile appearing to belong to Jahn pointed to the life of an avid gamer, with over 10,000 hours spent playing games like Team Fortress 2, Left 4 Dead 2, and Rust.