He left 16 years ago, carrying two small bags, one with his clothes, the other with his drum, or tabla. As a young man, Mr. Singh had undertaken religious studies, learning to perform the tabla during Sikh services, as well as singing and reciting prayers. In India, he worked at temples, or gurdwaras, in different cities before the family moved to New Delhi more than two decades ago.

At one service in New Delhi, Mr. Singh’s performance caught the attention of a Sikh priest visiting from Wisconsin. The priest offered to sponsor Mr. Singh for a visa to serve at the Oak Creek temple. In Wisconsin, Mr. Singh lived for many years on the grounds of the temple, eating his meals there. He eventually got a job in a convenience store, his family said, while continuing his work at the temple.

“He used to miss his children a lot,” said Magan Singh, a family friend in New Delhi.

Immigrants around the world often endure similar separation from their families. Millions of people from India and other South Asian nations work far from home — in the West, in Persian Gulf countries and elsewhere — sending back billions of dollars in remittances every year.

Surinder Singh Jodhka, a professor of sociology at Jawaharlal Nehru University in New Delhi, once lived in Wisconsin and said many of the Sikhs in the Milwaukee area were working-class migrants. He said that Sikhs in Punjab commonly aspired to go abroad and that long separations were typical. He said a strong sense of family duty was critical.

“That gives you a sense of satisfaction and keeps you going,” he said.

Sikhs began migrating to the United States about a century ago, and gurdwaras have since been erected across the country. Two of the men who were hurt, Santokh Singh and Punjab Singh, are traveling priests, Indian citizens, who shuttled between gurdwaras in Canada and the United States while their families remained in India. The son of Punjab Singh said different congregations would sponsor his father for weeks or months at a time because he had earned a reputation as a learned religious speaker.

“People loved his explanations,” Raghuvinder Singh said of his father. “People learned from him. He would go to Canada. He would go to England. He would go to the U.S.A.”