When Youngjin looked out of his office window and saw armored trucks and immigration enforcement officers running around with guns, he was surprised, but not worried.

The young South Korean was certain it had nothing to do with him. He was in the US only for a few weeks on a short-term visa, he thought to himself.

Then the armed agents burst into his room and ordered him outside. They handcuffed him, before attaching chains to his waist and ankles, and loaded him onto a bus bound for a detention center.

I panicked and my mind went blank. I felt sick, he told the BBC, now back home in South Korea.

I couldn't understand why I was being treated like this.

Youngjin is one of more than 300 Korean workers who were detained in the US state of Georgia earlier this month, in one of the largest immigration raids of Donald Trump's presidency to date. He and others interviewed for this article didn't want to reveal their real names in order to protect their identity.

US officials initially claimed the workers had been in the country illegally on incorrect visas, but eventually the two sides struck a deal allowing them to leave voluntarily without any penalties, so they could return to work there in the future.

Most of the workers were in the US temporarily, helping to build an electric car battery plant run by two South Korean companies, Hyundai and LG – part of a US push to get foreign companies to invest and manufacture more in the states.

LG said that many of its employees who were arrested had various types of visas or were under a visa waiver program. And so they were especially shocked by the raid.

They all said they had no idea why this was happening, or where they were being taken. I later learned that I was detained at the Folkston ICE Processing Center, added Chul-yong, a software engineer. He had been planning to stay for about a month but was arrested on his sixth day there. Youngjin, an engineer, echoes the sentiments of fear and confusion felt by many during the raid, which involved helicopters, drones, and officers pointing guns.

Describing their experiences in the detention center, many workers reported poor conditions, lack of basic hygiene, and severe emotional distress. The incident has now sparked discussions around human rights violations and strained relations between the US and South Korea.