What was the cause of John Henry Berry's death in Roll of Thunder, Hear my Cry?

John Henry Berry was set afire by drunken white men, and died of his injuries.

John Henry Berry was the owner of an old Model-T pickup, and had stopped for gas at a filling station in Strawberry.  Some drunken white men came up and accused John Henry of flirting with Sallie Ann, a white woman.  To avoid trouble, John Henry and his passengers Henrietta and Beacon got in the truck immediately and drove away, but after John Henry and Beacon had dropped Henrietta off at her home, the white men caught up with them and began ramming their truck.  Afraid that they would run out of gas before they could get home, John Henry and Beacon stopped at their uncle's place, but the men came and dragged the two young men and their uncle out of the house and set them afire.  John Henry died of his injuries, and Beacon and the uncle were left horribly maimed.

In the social climate in the South during the 1930s, blacks were largely at the mercy of bigotted whites.  When Henrietta went to the sheriff and told him what happened, she was called a liar and sent home (Chapter 2).  Although "everyone knows" that the Wallaces, who own the only local grocery and supply store, were the ones who "poured kerosene over Mr. Berry and his nephews and lit them afire", nothing is ever done about it (Chapter 4).  All the black community can do is endure, and commiserate with "angry, hopeless words" (Chapter 2).