Indian and foreign technology companies, including global outsourcing firm Accenture, closed offices and told staff to stay at home in the technology hub of Bengaluru on Tuesday after riots over the diversion of water from a river.

The violence was triggered by a court decision Monday that asked the southern state of Karnataka to divert some water from the Cauvery river to neighboring Tamil Nadu state.

Businesses in Bengaluru have faced four days of disruption this month because of protests about the water dispute and an unrelated trade union-organized strike on Sept. 2.

This week’s disturbances have been the most serious.

Prime Minister Narendra Modi called on Karnataka and Tamil Nadu to resolve their water dispute peacefully.

“The violence and arson seen in the last two days is only causing loss to the poor, and to our nation’s property,” Modi said on Twitter.

The Cauvery river has been the source of tension between the two states for more than a century, and violence over who gets access to its water has flared before.

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One person was killed Monday as police fired to stop protesters from torching vehicles with Tamil Nadu license plates.

Police said a curfew would be extended until Wednesday.

A Reuters witness said many shops remained shuttered Tuesday and fire trucks were outside a major shopping mall, which was closed and had netting draped from its walls, apparently for protection.

Television footage showed largely deserted streets as riot police patrolled.

Business Parks and Traffic Jams

Bengaluru, formerly known as Bangalore, is the capital of Karnataka and home to major Indian IT companies such as Infosys, Wipro, and Mphasis, as well as startups like Ola and Flipkart.

Multinationals like Samsung Electronics, Oracle orcl , and Amazon amzn also have offices there in modern business parks that have sprung up over the past decade or so.

Thousands of English-speaking Indians work in the city’s call centers and back offices.

To many, Bengaluru’s rise reflects the modern face of a booming India, but the city has also been a victim of poor urban planning and congestion that can produce traffic jams for hours.

Indian software giants Infosys and Wipro were among the big employers to stay shut Tuesday.

Accounting giant E&Y on Monday advised its workers to leave early and avoid traveling in vehicles with Tamil Nadu plates in Karnataka, and vice versa for those in Tamil Nadu.

It advised employees to work from home Tuesday.

A source familiar with the situation said outsourcing giants had closed Tuesday because not all staff could work from home.

A spokesman for Wipro said Saturday would be a working day to make up for the day off declared on Tuesday.