Defense Secretary Lloyd Austin transferred his duties to his deputy as he is hospitalized for treatment for symptoms “suggesting an emergent bladder issue,” according to the Pentagon.

Austin has been admitted into the critical care unit at Walter Reed National Military Medical Center, and it is “not clear how long Secretary Austin will remain hospitalized,” according to a statement released Sunday night from officials at the hospital.

Deputy Secretary of Defense Kathleen Hicks assumed the functions and duties of the top spot at the Pentagon shortly before 5 p.m., Maj. Gen. Pat Ryder, the Pentagon press secretary, said in a statement. The White House, the chairman of the joint chiefs of staff and Congress have been notified.

The rapid notification of Austin’s visit to the hospital – the first statement from the Pentagon was released within three hours – came after the defense secretary acknowledged failures in notifying the administration and the public about his previous hospitalization.