The Secret Service instructed employees who worked the Tulsa event to stay at home for 14 days when they returned from the weekend trip, according to two people familiar with the agency’s decision.

The order came in the wake of the discovery — hours before the president’s Saturday evening rally — that at least six advance staffers who helped organize the trip had tested positive for the virus, including two Secret Service employees. Another two advance staffers tested positive after Trump returned to Washington on Sunday.

On Tuesday, the Secret Service field office in Tulsa arranged for a special testing session at a hospital to determine if local agents had contracted the virus while assisting with the rally, according to two other people with knowledge of the testing. As part of the arrangement, doctors administered the test to both agents and some local officials in parked cars outside the hospital.