Frank Kameny, a prominent leader in the early gay rights movement, died Tuesday at 86, gay weekly the Washington Blade reported.

Kameny reportedly died of natural causes in his District of Columbia home. He was found unconscious and unresponsive shortly after 5PM by a tenant, who called emergency services. Officials believe Kameny died in his sleep.

After receiving a doctorate in astronomy from Harvard University and teaching for a year at Georgetown University, Kameny, an army veteran, was hired by the U.S. Army Map Service in 1957. But less than six months later, he was dismissed after a late night run-in with police in Lafayette Park, a traditional cruising area for gay men in the District of Columbia. Kameny legally challenged his firing in federal court – the first gay person to do so – but the Supreme Court refused to hear his petition and allowed a lower court's ruling against Kameny to stand. In 2009, the United States Government formally apologized to Kameny.

The firing prompted Kameny to become a gay rights activist. By 1961, he and Jack Nichols had co-founded the Mattachine Society of Washington, one of America's earliest gay rights groups.

The group asked for fair and equal treatment for gay federal employees, campaigned to overturn sodomy laws, and worked to remove the classification of homosexuality as a mental disorder in the manuals of professional medical associations.

In 1971, Kameny became the first openly gay person to run for Congress. He later served as the first openly gay member of the District of Columbia's Human Rights Commission.

In 2006, Kameny said: “I have tended not to adjust myself to society but with considerable success have adjusted society to me and society is much the better off for the adjustments that I have administered.”

Chad Griffin, president of AFER's board of directors, called Kamery an American hero.

“America has lost a hero today,” Griffin said in a statement. “Out and proud, Frank Kameny was fighting for equality long before the rest of us knew we could. Because there was one Frank Kameny, trailblazing and honest enough to speak out 50 years ago, there are now millions of Americans, coming out, speaking out and fighting for their basic civil rights. His is a legacy of bravery and tremendous impact and will live on in the hearts and minds of every American who values equality and justice.”