Three policemen lost their lives while others suffered injuries in clashes with workers of the banned Tehreek-i-Labbaik Pakistan in Lahore, officials said on Friday.
According to the story in Dawn, Lahore DIG (Operation) Spokesperson Mazhar Hussain was quoted as naming two of the dead officers as Ayub and Khalid.
Their photographs were widely shared on social media after journalist Mubashir Zaidi posted them Friday night.
The identity of the third official has not been released, according to Dawn, but a statement from the provincial chief minister stated that three policemen were martyred.
"Protesters also hurled petrol bombs on officials," Lahore's DIG Operation told Dawn, adding that officials tried to prevent them from vandalising and damaging public property.
An unnamed TLP spokesperson told Dawn that at least 500 workers had been seriously wounded while several had died.
A story by Associated Press says two demonstrators were killed.
Thousands of TLP supporters began their previously announced “long march” from Lahore to Islamabad, to demand the release of Saad Rizvi, who has been detained since April.
Rizvi was arrested last year amid protests against France over publishing blasphemous cartoons. TLP was demanding the country expel its French ambassador.
He was ordered to be released but the government has filed an appeal challenging the release saying it is a matter of maintaining law and order.
The Punjab government on Thursday night began deploying police and paramilitary personnel to prevent the demonstrators from leaving Lahore. They also blocked mobile services and cut off power in the area.
The violence erupted when police tried to stop the supporters from moving.
Sajid Saifi, a spokesman for TLP was quoted by AP as laying the blame on police and paramilitary forces for initiating the violence.
Police spokesman Rana Arif was also quoted by AP as saying the protesters threw stones.
Life was disrupted in Lahore due to the violence.
Punjab Chief Minister Usman Buzdar offered his condolences to the families of the deceased and ordered strict action against the perpetrators of the violence.
Earlier in the day he tweeted that he was forming a committee to hold talks with the TLP.
On Thursday, Interior Minister Sheikh Rasheed had said the government could not expel the French ambassador as it would impact its relations with the EU.
Rasheed is currently in Dubai to watch the T20 tournament.