Two people have been killed and 10 others injured in the Pakistani port city of Karachi.
Aftermath of Friday's violence
Violence broke out after large numbers of ethnic Pashtuns closed down the main highways connecting Karachi with the rest of the country.
Pashtun leaders had called a city-wide strike against what they called "increasing levels of victimisation of their community by local authorities".
Police fired teargas shells and have arrested some 50 people.
Critics of the authorities say they have been using the police to crack down on the city's Pashtun protesters.
Television footage showed one protester being badly beaten by a group of more than a dozen policemen.
Officials say arsonists have set fire to two banks, a petrol station, several vehicles and a police post.
Pashtuns say the city government, dominated by ethnic Mohajirs - descendants of settlers who came from India after partition - has been victimising them.
They say the government has deemed their Pashtun settlements and their transport associations illegal.
BBC's Shoaib Hasan in Karachi says the Pashtun-Mohajir rivalry has a long and bloody history, and has led to city-wide riots in the past in which hundreds of people have been killed.