Newark Mayor Ras Baraka was arrested while trying to inspect Delaney Hall, deepening the city’s legal fight with a private prison contractor.

Delaney Hall, a privately operated detention center in Newark, drew national attention on Friday as Mayor Ras Baraka, a Democratic candidate for New Jersey governor, was arrested outside the facility by federal immigration agents.

The mayor has been protesting its opening throughout this week, saying the operators did not get proper permits.