A U.S. Border Patrol technical search team is expected to join the search for a missing person after a deadly flash flood swept through Arizona’s Grand Canyon over the weekend.

Nearly 80 people have been rescued, while two hikers, John Giusti and Brent Rosenkranz, were confirmed dead.

A third man, 53-year-old pilot Timothy Smith, remains missing after the group was camping near the Bright Angel Creek area.

Search crews are using night-vision equipment and other tools to search the canyon, but additional rain and thunderstorms could trigger more flash floods, debris flows and rockfalls, The Guardian has reported.

Authorities say they currently have no reason to believe anyone else is missing, while rescue teams continue searching the dangerous and heavily damaged area.