Bob Seger Reveals Glenn Frey Had Been in the Hospital Since November

The singer reveals details of the guitarist's final days.

As the world mourns the loss of the iconic Glenn Frey, more details have begun to surface of his final days.

Bob Seger, friend to the Eagles cofounder, revealed to the Detroit Free Press that the guitarist had been in the hospital since November and even was put into a medical induced coma.

WATCH: Eagles Guitarist Glenn Frey Dies at 67

"First he caught one set of pneumonia, then he caught a very virulent set of pneumonia," Seger shared. "They were trying like hell to keep him alive. He'd been at Columbia Medical Center since November. [Eagles manager] Irving [Azoff] pulled every ace out of the hole. He had the eight best specialists working on Glenn. About a month ago, they had to throw up their hands.”

Frey passed away on Monday due to "complications from rheumatoid arthritis, acute ulcerative colitis and pneumonia," according to the musician's family.

"He was a joy to be around," Seger added. "He had a fantastic sense of humor. He was whip smart, just brilliant, even at 18 years old when I met him."

WATCH: Don Henley Reacts to Glenn Frey's Death: 'Glenn Was the One Who Started It All'

Despite his stay in the hospital, a source revealed to ET that his death was “a shock to everyone.”

“He has been very sick for the last few months, but the band really did believe he would heal fully,” the insider said.

Following the announcement of his death, celebrities took to Instagram and Twitter to remember the rock legend. To see some of the heartfelt tributes, watch the video below.