On this day, 33 years ago, former San Francisco City Supervisor Dan White took a gun to City Hall.

He climbed through a lower-level window to avoid metal detectors and proceeded to Mayor George Moscone’s office.

White had resigned his office and went into Moscone’s office hoping to be re-appointed to the seat he’d resigned from. When Moscone refused, White shot and killed him.

With extra ammunition, he proceeded to the office of Harvey Milk, who in 1977 was elected to the San Francisco Board of Supervisors, becoming the only the third openly gay man in U.S. history to be elected to public office.

Harvey Milk, May 22, 1930 – November 27, 1978

White shot Milk five times — the final two shots had White pressing his gun directly at Milk’s skull, according to the medical examiner.

Prior to his death, Milk had recorded a message after receiving several death threats simply because he was gay. The message said:

“If a bullet should enter my brain, let that bullet shatter every closet door.”

Milk served only 11 months on the Board of Supervisors, but his high profile election victory gave hope to millions of gays and lesbians across the country that a day would come when they could live without fear of discrimination.

As a Supervisor, Milk worked to secure passage of San Francisco’s landmark gay rights ordinance that extended employment protections to gays and lesbians in San Francisco, and became a model for anti-discrimination legislation throughout California and the nation.

On May 21, 1979, White was acquitted of the first degree murder charge, but found guilty of voluntary manslaughter of both Milk and Moscone.

While White’s confession included statements such as “I was on a mission” and “I wanted to kill four of them,” he was found innocent premeditated murder due to his “poor diet.” White’s lawyers successfully argued that White had been consuming many sugary foods, which led to his mental state. This became known as the “Twinkie Defense.”

White was sentenced to serve seven and two-thirds years, but the sentenced was reduced for time served and good behavior, meaning White would be released in only five years.

The sentence sparked outrage in San Francisco’s Castro District, and protestors marched from the Castro to City Hall, chanting “Avenge Harvey Milk” and “He got away with murder.” Eventually the crowd swelled to over 3,000 and riots broke out — angry residents lit police cars on fire, shoved a burning newspaper dispenser through the doors of City Hall, and cheered as the flames grew.

But only hours after the riots had ended, police made a retaliatory raid on a San Francisco gay bar. Two dozen arrests were made and in the following weeks, gay leaders refused to apologize for the riots. This is what gave them political power and led to the election of Mayor Dianne Feinstein.

Feinstein then appointed a pro-gay chief of police who actively recruited gays into the city’s police force.

Dan White served five years of his seven-year sentence. Two years later, he was found dead after committing suicide in his garage by carbon monoxide poisoning.

Feinstein, now a U.S. Senator, is leading the way for LGBT equality by sponsoring the “Respect for Marriage Act,” which would repeal the anti-gay Defense of Marriage Act (DOMA).