The Canada Border Services Agency has arrested several people at a racetrack in Vancouver, according to witnesses.

The agency confirmed to CTV News Vancouver that there is an ongoing investigation at the Hastings Racecourse, but it would not provide details including how many people were arrested and the nature of the case.

"The CBSA conducts enforcement actions when it is believed that a contravention of the Customs Act or the Immigration and Refugee Protection Act has occurred," it said in an email to CTV News.

An employee at the racetrack, who didn't want to be identified, said they saw about two dozen people getting arrested around 6:30 a.m. Monday.

Hastings Racecourse confirmed "a number of individuals" were escorted off its property, adding the people were employed by private horse owners.

"These individuals were working in the backstretch under the employment and supervision of various horse owners and trainers that are stabled at Hastings Racecourse to race," said Darren MacDonald in a news release.

MacDonald said those arrested were not Hastings Racecourse employees or affiliated with Great Canadian Gaming Corporation.

Patti Tubbs has been working at the racetrack for decades. She said she was disgusted about how the situation was handled.

"It was demeaning, it was not fair, they were treated poorly," said Tubbs, who is a photographer for Hastings Racecourse.

Witnesses say the raid happened in several barns, and claimed  CBSA officers targeted anyone who wasn't white.

"Immigration came through and arrested all the Mexicans, looking for illegal immigrants," Tubbs said.

She said she knew many of the workers personally.

"They were hard working people," she told CTV. "They would send money home back to their families living in Mexico. They were really nice people."

Tubbs said staff members were given little explanation as to what was happening.

"I'm hearing it's because their papers weren't in order."

The CBSA has 48 hours to decide on how to proceed after arresting an individual.