In search of four undocumented immigrants, federal agents raided a mushroom farm facility in Chester County and took into custody nine workers there, according to witnesses and the owner of the farm.

None of those nine workers were the four that officers with Immigration and Customs Enforcement were reportedly looking for.

ICE came onto the private property of a processing facility owned by South Mill Mushrooms Wednesday morning. The end of the raid, including the arrests of two men, were caught on video and posted to social media.

Michael Pia, the fourth-generation owner, told NBC10 on Friday that ICE did not make clear whether they had a warrant to come onto the property.

"I do not believe they had a warrant or no one told me there was one," Pia said. "They just came onto the property and at the apartment complex across the street. I was under the assumption they were allowed to."

"When an HR supervisor talked to the agents, they were already on the property. We're actually kind of looking into that," he said.

The raid on private property is the latest in a string of high-profile immigration busts to occur in the Philadelphia region since the beginning of the year. In March, nearly 250 were arrested across the region along with Delaware and West Virginia. Also in March, ICE officers made three early morning stops of vans filled with workers heading to job sites in Berks County.

The vans were targeted because they made frequent stops to pick up Latino workers, according to an immigration attorney in Reading who is investigating the stops on behalf of some detainees.

That attorney, Bridget Cambria, also questioned Friday the lawfulness of ICE's Chester County raid, noting that they would need a warrant to enter private property.

Two spokesman for the ICE field office in Philadelphia did not respond to an email seeking a government account of the mushroom farm raid. It is unclear where the men are being detained, but many suspected undocumented immigrants arrested in Pennsylvania are taken to York County Prison, which has a contract with the federal government.

Pia said the workers detained are not employees of South Mill, but are assigned to the processing plant on Starr Road in Kennett Square through a subcontractor. He said he did not immediately have the name of the subcontractor who employed the men.

ICE told farm supervisors that the officers came looking only for four individuals wanted by authorities, but Pia said he was told that none of the nine arrested were the people ICE was looking for.

Witnesses to the ICE raid Wednesday told Telemundo62 that the scene was chaotic as workers at the plant realized who the ICE officers were.

The witness said "no one knew where to run but everyone scattered."

ICE officers in "la migra" cars were at the mill for three hours after rounding up nine of those workers who initially tried to flee.

The witness added that ICE officers told people at the plant that "we'll be back."

A witness captured the end of a raid at a processing plant in Kennett Square, Wednesday, April 26, 2017.

Pia said it's the third such raid in the mushroom mecca surrounding Kennett Square that he's heard of, but the first at any of his properties. South Mill Mushrooms dates to 1932 when, according to the company's website, "John Pia, an Italian immigrant, began operating a small mushroom farm in southeastern Chester County."

Over the decades, the business expanded until in 1982, the Pia family was able to purchase one of the region's largest mushroom farms from the Clorox Corporation.

The day of the raid, the company honored a 20-year veteran of the company, Roberto Alvarez, on its website as part of what the company calls "#WhoWeAreWednesday."

"Roberto was born in Puebla, Mexico and migrated to the United States with his parents and siblings when he was 11 years old. Roberto began working for us in 1997 as a Mechanic’s Helper. Several years later, he was promoted to Assistant Manager and since 2007 he has been the Manager of the Maintenance shop at our Tunnel operation. Roberto enjoys the new challenges he faces every day and the people with whom he works."