Ten Pakistan protesters killed by gunmen in Karachi
At least 10 people have died after gunmen opened fire on a political rally in Pakistan's volatile southern port city of Karachi, police say.
Thirty-five other people - including two journalists - were injured.
The procession was made up of ethnic parties who were denouncing proposals for a new province to be created for the Urdu-speaking urban majority.
Hundreds of people have been killed in Karachi - in the southern Sindh province - since January 2012.
Karachi has long suffered outbreaks of violence, either carried out by the Taliban, criminal elements or because of turf wars between rival political and ethnic groups.
At least 800 people died in politically motivated attacks in the city last year.
Ethnic Sindhis, who mostly live in rural areas, have warned that attempts to divide the southern province of Sindh could lead to widespread violence.
Shafiq Baloch, who was taking part in Tuesday's rally, told the BBC the shootings happened as marchers approached the city centre.
"As soon as we crossed the street, we were fired on. I cannot tell you how many of our young men got injured. You can see my bloodied clothes as I have picked up many bodies myself."
Several shops and about a dozen vehicles were set on fire after the shootings, and the security forces were attacked.
The BBC's Syed Shoaib Hasan in the city says that the violence began when the sound of gunfire reverberated around Karachi, forcing terror-stricken marchers to seek cover in narrow lanes and alleyways.
Our correspondent says that in the aftermath of the attack the marchers turned into rioters, but now the disturbances have been brought under control.
However, tension is expected to resurface on Wednesday, when political parties participating in the rally have called for a strike.
The rally was a response to recent demands for a separate province for the Muhajir Urdu-speaking ethnic group. The group dominates much of urban Sindh - including Karachi - through the MQM political party.
MQM leaders deny they have anything to do with the demand for a separate province - although they maintain Karachi should remain administratively separate from Sindh.
This stance is opposed by Sindhi nationalist groups and has led to increasing turmoil in the city.