Former 49ers wide receiver Dwight Clark died Monday after a battle with ALS. He was 61 years old.

Clark’s wife, Kelly, posted the news on her husband’s Twitter account. She said he passed peacefully surrounded by many of the people he loved most.

I’m heartbroken to tell you that today I lost my best friend and husband. He passed peacefully surrounded by many of the people he loved most. I am thankful for all of Dwight’s friends, teammates and 49ers fans who have sent their love during his battle with ALS. Kelly Clark.

He was responsible for one of the most iconic plays in NFL history that began our run of Super Bowl championships, but to me, he will always be an extension of my family. I love him and will miss him terribly. Our hearts and prayers are with his wife Kelly, his children and the entire Clark family.

Recently, I underwent an annual physical, during which it was discovered I have lymphoma. Over the past week, I have undergone more testing to determine the course of treatment, which is scheduled to start in the very near future.

The doctor’s outlook for the treatment and the prognosis is positive, and so am I.

I will continue to work as much as the treatment process will allow, and as they know, when I am not in the office, I will be in constant communication with Pat (Shurmur), Kevin (Abrams) and the rest of our staff.

I am thankful to John Mara and Steve Tisch and our organization for their support and encouragement, and to Ronnie Barnes for his guidance and assistance. And, of course, to my wife Joanne and our children for their love and support.