Sikhs wield swords during their clash inside the complex of the holy Sikh shrine, the Golden Temple, in the northern Indian city of Amritsar on June 6. (Munish Sharma/Reuters)

Rival groups of turban-clad, sword-brandishing Sikhs clashed today in the confines of the Golden Temple of Amritsar, Sikhism's holiest site. Television footage showed alarming scenes of grown, bearded men bludgeoning each other with various weapons. According to reports, at least 12 people were wounded and nearly two dozen have been arrested.

The violence was apparently triggered by a minor disagreement between two different groups over who could speak first at a ceremony.

But this was not just any ceremony. Friday marked the 30th anniversary of Operation Bluestar, when the Indian military launched a five-day-long raid on the Golden Temple, which was then occupied by armed Sikh separatists. Casualty counts from the operation remain unclear, with estimates that some 500 people were killed, including about 80 soldiers. Sikh groups say the number of civilians killed was much higher.

The storming of the 16th century temple, the most important shrine in all of Sikhism, angered many Sikhs, including the bodyguards of then-Indian Prime Minister Indira Gandhi. A few months later, two of them gunned the prime minister down, an assassination that led to hideous anti-Sikh riots in Delhi and elsewhere in northern India that claimed thousands of lives.

Pigeons fly by as a Sikh man takes a dip in the sacred pond of the Golden Temple after a prayer and remembrance meet for the Sikh separatists who lost their lives during Operation Bluestar in 1984 at the Golden Temple, the holiest of Sikh shrines,  in Amritsar, India, on June 6.  (Raminder Pal Singh/EPA)

Hardline Sikh separatists, who seek an independent Sikh homeland called Khalistan, are now a small fringe. The many Sikhs gathered at the Golden Temple on Friday were there to mourn those lost three decades ago. But tensions were inflamed after one group's request to address the gathering was denied by another group charged with the custodianship of the holy site. According to the Indian Express, "a group of radicals brandished swords," chanted "pro-Khalistani slogans" and started "thrashing" the official who had denied their leader a chance to speak. The scenes that followed speak for themselves.

Sikh activists clash with members of the Shiromani Gurudwara Prabhandak Committee (SGPC) during commemorations for the 30th anniversary of Operation Bluestar at the Golden Temple in Amritsar on June 6. (Narinder Nanu/AFP/Getty Images)

“Today we were supposed to have a solemn remembrance for the martyrs of 1984,” said Prem Singh Chandumajra, a Sikh politician. “So what has happened is very sad.”

Sikhism emerged in what's now Pakistan and northern India in the 16th century. It eventually drew a somewhat militarized following, leading to a preponderance of blades during particular religious rites.