YUMA — Immigration agents raided the construction site of Yuma's newest high school looking for undocumented workers, detaining six workers for questioning and searching the offices of a site contractor.

About 50 agents from U.S. Immigration and Customs Enforcement and the Border Patrol conducted the raid Tuesday morning, with backup from Yuma police and a helicopter.

Yuma Union High School District Superintendent Tim Foist said the six who were detained were expected to return to work once their status was cleared. All were employees of contractors working on the $50 million Gila Ridge High School.

Foist said the raid was an example of the national illegal-immigration debate hitting home, and said he supported the checks.

"We said, 'Do not hire illegals,' "Foist said. "And we think that's been followed. We believe our job site is being handled in the right way."

Of the six workers who were detained, two were being held to clarify their immigration status, said Jim Pilkington, owner of Pilkington Construction Co., the firm managing subcontractors involved in the project. One of those workers had been on the job for 10 years.

"We do our homework," he said. "We have pretty strict policies to make sure we do not hire illegal aliens."

ICE spokesman Russell Ahr said the agency has conducted similar work-site enforcement investigations in the past, and more are expected as the agency shifts its enforcement "thrust" under the Secure Border Initiative. The added focus is on employers who hire illegal workers.

"We're looking to get criminal indictments against people who knew they were illegal and put them to work," Ahr said.