When they spotted a stranger parked near their temple, two Sikh men came out and asked if he would like tea. He responded by shooting them both dead and walking inside.
Satwant Singh Kaleka, an immigrant from India who worked long hours at a gas station before saving enough money to build the temple, quickly sensed danger and rushed worshipers into hiding, likely saving many lives.
Armed with only a fruit knife, the 65-year-old Kaleka lunged as the assailant - white supremacist US Army veteran Wade Michael Page - changed bullet clips.
"My dad took five gunshot wounds, all in sporadic places - under the armpit, in the inner thigh," said his son Amardeep Kaleka, who keeps the fruit knife and his father's bloodied turban as mementos.
"My dad had a bunch of blood and skin and hair under his nails when we saw his body, so they fought rigorously," he added.
Then Page simply walked back out. By then, police had arrived, and Page shot an officer multiple times before taking his own life.
The massacre on August 5, 2012 in the Milwaukee suburb of Oak Creek left six members of the temple dead, with another critically injured. The officer, Lieutenant Brian Murphy, was seriously hurt but was wearing a bulletproof vest and survived.
The attack was the deadliest against the US Sikh community, but it was not the first or the last.
Days ahead of the massacre anniversary, another Sikh temple, known as a gurdwara, found the word "terrorist" - in one instance misspelled - spray-painted on the walls.
That vandalism took place in California, where an 81-year-old Sikh man was severely beaten with a steel pipe near his gurdwara in May. In 2011, two other elderly Sikhs were shot and killed as they strolled near California's capital Sacramento.
Sikh men are easily visible as their faith, founded five centuries ago in South Asia, requires them to wear turbans and keep beards.
Anti-Sikh violence spiked following the September 11, 2001 attacks as some assailants appeared to incorrectly link Sikhs with radical Islam. One man, who shot dead a Sikh gas station owner in Arizona days after the attacks, boasted of being a US "patriot."
Since the Oak Creek massacre, a panel has recommended that the FBI begin compiling statistics on hate crimes specifically against Sikhs as well as several other groups.
US Representative Joe Crowley, a Democrat from New York City who pushed for the change, called the move "significant progress" and hoped that the Oak Creek massacre would increase awareness for Sikhs.
Crowley embraced the cause of Sikh civil rights in the aftermath of September 11 attacks, in which his cousin died.
"I saw Sikh American gentlemen on the street, in suit and tie with oversized handheld American flags in their lapels," Crowley told AFP.
"And I thought, that's so sad. These guys, they're not responsible for anything, and yet they feel compelled to overly demonstrate their patriotism so that no one beats them up or kills them," he said.
Amardeep Singh, co-founder of the Sikh Coalition advocacy group, said more needed to be done to bring change.
He called for US airport security to end wand searches of turbans, saying it contributed to a false association of Sikhs with terrorism.
Singh also hoped that schools would teach more about Sikhism. Surveys by the Sikh Coalition in New York and San Francisco area found that more than half of Sikh children reported being bullied.
Can more be done?
Well before the massacre, President Barack Obama started the first White House celebrations for the birth anniversary of the founder of Sikhism, Guru Nanak.
But while Obama has regularly consoled survivors of US shootings, he did not go to Oak Creek. His wife Michelle and senior aides went instead.
Sikh leaders have not criticized Obama for his absence, mindful that the nation's first African American president was in the midst of an election campaign in which some opponents sought to portray him as foreign.
But Kaleka said the White House this year declined invitations for Obama to attend or make a video statement to an inter-community service planned for the anniversary.
"My reaction was, you guys crack me up. Because this affects black people, this affects Jewish people, this affects everybody," said Kaleka, a 35-year-old filmmaker who divides his time between Milwaukee and California.
Kaleka feared that leaders were reluctant to confront deeper problems that led to the death of his father and others, such as US gun culture and white supremacism.
"This guy was an Army veteran. He walked through that killing zone with an ear plug in his right ear knowing he was going to fire more times from his right hand. He was a sharpshooter," Kaleka said.
"It was unbelievable how much hate he had, but he was trained by our government. And now the government wants to put its hands up and say maybe we shouldn't be a part of this," he said.
Kaleka rejected assertions that Page, a 40-year-old who had worked in Army psychological operations, misidentified Sikhs as Taliban or mainstream Muslims.
"That's such an outsider perspective, because everything we know about this person is that he knew what a mosque was," Kaleka said.
"The mosque was only four minutes away from our temple. The mosque has amazing domes - it's beautiful, it's a spectacle and everybody knows it," he said.
"He attacked us, because we're figures of change. We look different," he insisted.
The Southern Poverty Law Center, which tracks hate groups, said it was aware of Page for more than a decade as he was active in white supremacist rock bands.
But Mark Potok, a senior fellow at the center, said there was nothing "particularly obvious" about Page.
"The sad reality is that Wade Page had very unpleasant views and yet they were essentially indistinguishable from the views of tens of thousands of other people," Potok said.
"The bottom line is that there are thousands and thousands of Wade Pages, at least until the point when he became a mass murderer," he said.