Homeland Security Secretary Alejandro Mayorkas has tested positive for COVID-19, DHS said on Tuesday – just days after he attended an event with President Biden.

A DHS spokesperson said that contact tracing was underway after Mayorkas tested positive Tuesday morning as part of routine pre-travel protocols.

"Secretary Mayorkas is experiencing only mild congestion; he is fully vaccinated and will isolate and work at home per CDC protocols and medical advice," DHS spokesperson Marsha Espinosa said. 

The diagnosis comes after Mayorkas attended the 40th Annual National Peace Officers’ Memorial Service at the U.S. Capitol alongside President Biden on Saturday. While it was not clear what sort of contact the two men had, Biden mentioned Mayorkas by name at the event.

"To Secretary of Homeland Security Mayorkas, thank you for being here and for the great job you’re doing for us," Biden said. "Thank you very, very much.  And it's a tough job."

Additionally, images from the event show Mayorkas stood close to Biden and first lady Jill Biden at one point during the outdoor event, without masks. 

But the White House said that no White House principal had been determined to be a close contact of Secretary Mayorkas, given that the most recent contact took place outside of the 48-hour close contact window.

Mayorkas has been in the spotlight in recent months for the Biden administration’s handling of the crisis at the southern border. More than 200,000 migrants were encountered in July and August -- and the administration has been continuing a limited use of Title 42 public health protections to return migrants due to the risk of COVID-19.

However, the administration has come under fire for releasing migrants into the interior, often without testing for the virus. Chris Magnus, Biden’s pick to lead Customs and Border Protection, on Tuesday told lawmakers that he was committed to making sure migrants are tested before being released into the U.S.