Gilbert Baker, the creator of the rainbow flag that has become a widely recognized symbol of gay rights has died. He was 65.

Baker was found dead Friday at his New York City home. The city medical examiner’s office said Saturday that he had died of hypertensive heart disease.

Baker was born in Kansas and served in the U.S. Army from 1970 to 1972.

He was stationed in San Francisco in the early days of the gay rights movement and continued to live there after his honorable discharge.

According to Baker’s website, he taught himself to sew and began making banners for gay and anti-war marches, creating the rainbow flag in 1978.

Baker said in a 2008 interview that he knew instantly from the way people reacted to the flag that it was “going to be something. I didn’t know what or how … but I knew.”

Baker was part of a circle of San Francisco gay activists that included Harvey Milk, the city supervisor who was assassinated in 1978, and Cleve Jones, who created the Names Project AIDS memorial quilt in the 1980s.

In an interview Saturday, Jones recalled the rainbow flag’s first appearance at the 1978 gay pride parade.

“It was quite amazing to stand there and watch all these thousands of people turn off Market Street into San Francisco Civic Center Plaza and march beneath these giant flags that were flapping in the wind,” Jones said. “People looked up and faces lit up and, without any explanation, this was now our flag.”

The flag was initially eight colors, but it was cut to six because of the limited availability of fabrics, Jones said. He said Baker rejected advice to patent the rainbow flag design and never made a penny off it.

Baker also designed flags for civic occasions including the inauguration of Dianne Feinstein, now California’s senior U.S. senator, as mayor of San Francisco.

Baker moved to New York in 1994 and created a milelong rainbow flag for the gay pride parade, which that year commemorated the 25th anniversary of the 1969 Stonewall uprising.

Current San Francisco Mayor Edwin Lee said in a statement that the rainbow flag “has become a source of solace, comfort and pride for all those who look upon it.”

“Gilbert was a trailblazer for LGBT rights, a powerful artist and a true friend to all who knew him,” Lee said.