The crush began as the audience of thousands was leaving the performance of Ungu, a popular Indonesian guitar band, at a sports stadium in the town of Pekalongan, Central Java province, late Tuesday, Sgt. Slamet said.
"People were very rough and began pushing," he told The Associated Press. "The victims were trampled to death."
Police took 10 bodies to the nearest hospital, while dozens of others had minor injuries, said Slamet, who like many Indonesian goes by a single name.
Concert organizers were not immediately available for comment.