Billionaire Paul Allen, the owner of the Seattle Seahawks and co-founder of Microsoft, has died.

His death was announced Monday evening on the Vulcan Inc. Twitter page. Allen founded Vulcan Inc. “to make a positive difference in the world,” according to the website. 

“Mr. Allen died on Monday afternoon, October 15, 2018, from complications of non-Hodgkin’s lymphoma in Seattle,” Vulcan said in a statement.

Allen announced his non-Hodgkin’s lymphoma returned earlier this month. He previously fought the disease in 2009.

“I’ve begun treatment & my doctors are optimistic that I will see a good result,” he said in an Oct. 1 tweet. “Appreciate the support I’ve received & count on it as I fight this challenge.”

Allen’s sister released this statement from her family through Vulcan:

“My brother was a remarkable individual on every level. While most knew Paul Allen as a technologist and philanthropist, for us he was a much loved brother and uncle, and an exceptional friend.  

Paul’s family and friends were blessed to experience his wit, warmth, his generosity and deep concern. For all the demands on his schedule, there was always time for family and friends. At this time of loss and grief for us – and so many others – we are profoundly grateful for the care and concern he demonstrated every day.”