Riots broke out in the technology hub of Bengaluru on Monday over a long-running river water dispute with the neighbouring state, with protesters setting cars and buses on fire and pelting people with stones.

Riot police took to the streets, and public gatherings were banned in a bid to rein in the unrest, while police said the local metro network had been temporarily suspended.

The violence erupted after India’s Supreme Court ordered Karnataka state, where Bengaluru is located, to release 12,000 cubic feet of water per second per day from the Cauvery river to the neighbouring state of Tamil Nadu until September 20.

The river has been the source of more than a century of tension between the states, and there have been outbreaks of violence before.