The incident took place last night at Chidwai village near Ramgarh, when Suraj, along with his brother, raised objection to the digging of land close to their farm by the four persons, police said.
Suraj's farm is located near Rooparel river in Ramgarh. After an argument, the accused identified as Hakku, Jamsher, Ajroo and Mosim allegedly crushed Suraj under the JCB, Additional Superintendent of Police Alwar, Paras Jain said.
Suraj was admitted to a local hospital with critical injuries where he died during treatment.
An FIR has been registered against the accused, police said, adding that efforts are on to nab them.
Meanwhile, the villagers claimed that the police is hand-in-gloves with the sand mafia and said that they would protest if Suraj's killers are not arrested.