KOLKATA, India (AP) — Police say a mob beat to death the CEO of an Indian jute factory in a dispute over increasing their working hours.

Police Superintendent Sunil Chowdhury said four people were arrested Sunday and two more on Monday after the attack at the North Brook Jute Mill in the eastern Indian state of West Bengal.

The mob had stormed the office of 60-year-old CEO H.K. Maheswari after he denied their request to work and be paid for 40 hours instead of 25.

Maheswari died on the way to a hospital. A manager and a security guard were also hospitalized with injuries.

West Bengal is known for its combative labor unions backed by political parties. Chief Minister Mamata Banerjee blamed the violence on unions run by opposition parties, which denied any role.