NEW DELHI — Riots erupted across the Punjab region of India on Monday in response to the killing of the leader of a Sikh sect who died after an attack on a temple in Vienna on Sunday. At least one person was killed and the authorities placed four towns under a curfew after a day of violent protests following the attack in Austria on the sect leaders, who were visiting the large Sikh community in Europe. While in Vienna, six young Sikh men armed with guns and knives stormed into a hall where hundreds of worshipers had gathered and shot at the sect leaders, said S. R. Heer, a senior official at the sect’s hospital and school in Jalandhar, a large provincial town in Punjab. One of the leaders, Guru Sant Rama Nand, died of his injuries, while the other, Sant Niranjan Dass, was in stable condition following surgery, Mr. Heer said. The two men were the leaders of the Ravidass sect, Sikhs who revere a saint of the same name believed to have been born in the 15th century to a family of leather workers, considered “untouchables” or outcastes, and known today as Dalits. Though the bloodshed happened a continent away, news of the attack, by text messages and mobile phone calls sent from the vast community of Sikh émigrés in Europe, came to Punjab almost instantly. The rioting quickly followed. Television stations in India beamed images of sect members parading through the streets of Punjab with swords, metal rods and sharpened sticks aloft. The rioters smashed cars and set fire to empty trains, snarling road and train traffic through one of the most prosperous provinces of India, police officials said. Bank machines, car dealerships and buses were destroyed. In Vienna, 16 people were wounded in the melee that followed the attack, The Associated Press reported. “We are dealing with a very tense situation,” said Kuldeep Singh, Deputy Inspector General of Police in Jalandhar, one of the worst hit towns. The army fanned out to quell the violence, and top officials of the newly sworn-in government, which was elected this month, issued statements of dismay and called for calm. “Sikhism preaches tolerance and harmony,” Prime Minister Manmohan Singh, himself a Sikh, said in a statement. “I appeal to all sections of the people in Punjab to abjure violence and maintain peace.” In principle, Sikhism rejects caste divisions; one of its main tenets is the equality of all believers. But the existence of caste-based sects within Sikhism illustrates how tenacious divisions that have existed for millennia can be. The motive of the attack on the Vienna temple was unclear. Some mainstream Sikhs disapprove of the religious practices of the Ravidass members, who worship their own saints. Mainstream Sikhism reveres only its holy book, known as the Guru Granth. But these theological disputes have rarely provoked violence between sects, experts say. Though vastly diminished, discrimination against Dalits remains a force in everyday life among Sikhs in the countryside, said Surinder Jodhka, a sociologist at the Jawaharlal Nehru University in Delhi who studies caste in Punjab. But, Mr. Jodhka said, Dalits have successfully integrated themselves into mainstream Sikh society, and violent caste conflicts are unusual. Punjab has one of the highest shares of Dalits, and like Dalits from other Indian states, they have climbed the social ladder by venturing out of their villages to work, earn and remake themselves. Many Dalit Sikhs, devotees of the Ravi Dass sect, started migrating to Europe in the 1960s, helped set up Ravi Dass temples, known as gurdwaras, and played host to preachers from Punjab, for whom Europe and North America became important fund-raising bases. Hari Kumar and Somini Sengupta contributed reporting.