Thousands of people gathered to pay their respect and leave flowers in Palace Square in the center of Oslo on Friday after the passing of King Harald V earlier. Photo by Thomas Andersen/Pool/EPA

Aug. 28 (UPI) -- King Harald V of Norway died early Friday in an Oslo hospital where he was undergoing treatment for a rare blood disorder. He was 89 years ol.

He passed peacefully at 6:35 a.m. local time, according to the Royal Palace, which said the royal flag was flying at half mast on the palace roof.

Family were called to his bedside after his condition worsened on Thursday at the national hospital, 10 days after he was admitted suffering from complications from haemolytic anaemia, a rare blood condition that depletes the number of red blood cells causing fatigue and shortness of breath.

Harald leaves behind his wife Queen Sonja, also 89, the new king, Haakon, their daughter Princess Märtha Louise and six grandchildren.