At least one more Secret Service agent has tested positive for COVID-19, and several others have fallen ill.

The information, released Thursday evening, is based on the claims of two anonymous senior administration officials, according to the New York Times. Ahead of Vice President Mike Pence’s visit to Arizona, at least one Secret Service agent on the ground in Phoenix tested positive for the coronavirus, with other agents and federal officers exhibiting symptoms. The agency urged the VP’s office to delay the trip by a day, which it ultimately did.