NEW DELHI — A young woman traveling in Punjab on Wednesday evening was killed after she and her mother were molested and thrown from a private bus by a group of men, the mother said.

Four men were arrested on Thursday in connection with the case: the driver and conductor of the bus and two other employees of the bus line. They were variously charged by the police in the Moga district with murder, attempted murder, molestation and conspiracy, as well as violating a law relating to crimes committed against members of India’s lower castes, to which the two women belonged.

The young woman sustained a head injury and died immediately, according to a police constable in the district, who declined to give his name because he was not authorized to speak to the news media. The constable said the mother was taken to a hospital for treatment.

The company that operated the bus is owned at least in part by the family of Parkash Singh Badal, the chief minister of Punjab state, according to local news media reports. Mr. Badal’s son, Sukhbir, is his deputy chief minister, and his daughter-in-law, Harsimrat Kaur Badal, is a minister in the central government.