Immigration and Customs Enforcement detained 160 illegal alien workers in a raid on Tuesday, federal authorities said, at a manufacturing company called Load Trail, about 100 miles northeast of Dallas.

Using helicopters and assault weapons, more than 300 agents apprehended more than 100 people.

“I know I just heard helicopters everywhere and I saw a whole lot of people running and so I turned to run and the first corner I hit I got guns drawn down on me,” an unnamed witness told ABC News.

The search involved agents from New Orleans, Houston and San Antonio, Katrina Berger, Homeland Security’s special-agent-in charge of investigations, told ABC. The agency launched the investigation after getting a tip that Load Trail may have knowingly hired illegal aliens.

“I knew these were clearly illegals. This is not the way we are supposed to be hiring,” Berger said. “They told me to keep doing my job — that if they were visited by ICE again, they would simply pay the fine and go on.”

The raid, part of an ongoing investigation into the trailer manufacturing company, is believed to be the largest of its kind in a decade, ICE’s Homeland Security Investigations Office told the Dallas Morning News.

Detention centers in Dallas and Oklahoma have been processing the undocumented workers for deportation, ICE said.

Factory worker Dennis Perry told the Dallas Morning News, “I feel sorry for them. They are trying to support their families. I am never going to be against people who want to support their families. But there is a right way to do it. I couldn’t call anyone on them. In my work, you get to know a lot of these guys.”