Her body was later found for days later and police deduced she had been strangled to death.
Two people were killed by gunshot wounds as angry protesters clashed with police, two others sustained bullet injuries.
Ameen Ansari, who was away on a pilgrimage in Mecca at the time of his daughter's murder, has accused the police in Kasur of negligence and said that an immediate response when the alarm was raised could have saved Zainab's life.
Kiran spoke about how she had felt as a mother on hearing Zainab's killing.
Pakistanis expressed their shock on social media using the hashtag "justiceforZainab".
The protesters also erected barricades at several roads cutting the city with rest of the country with no police in sight. Nowadays she was living at her aunt's house because her parents went to perform Umrah.
"We want the culprit to be brought in front of us".More news: What Are The Side Effects Of Flu Shot 2017/2018?
Opposition leader Imran Khan urged authorities to act swiftly, saying in a Twitter message that "the condemnable and horrific rape of the minor had once again exposed how vulnerable children are". Even though the report did not confirm rape, the doctor said the victim's hymen was ruptured and she might have been sodomised. When Zainab was missing her, uncle Muhammad Adnan reported an FIR on Jan 4 in Sadar Police Station of Kasur.
Zainab's death comes less than three years after a scandal in Kasur when at least 280 children were filmed being sexually abused by a gang of 25 men, who blackmailed their parents by threatening to leak the videos.
The murder has prompted calls for action from cricketer Imran Khan and Nobel Peace Prize victor Malala Yousafzai.
People attend a funeral of a Pakistani girl who was raped and killed, in Kasur, Pakistan, today.
'This is not the first time such horrific acts have happened. However, lawmakers have said that the family is partly to be blamed for the crime.
The Senate Standing Committee on Interior also took notice of the incident and ordered the Punjab police to take swift action.
Punjab Chief Minister Shehbaz Sharif visited the victim's family Thursday morning assuring them the culprits will be caught and punished, local media reported.
The cleric is a staunch political rival of the ruling Pakistan Muslim League party and he has led violent rallies in the capital, Islamabad, since 2014 after eight of his supporters were killed in anti-government rallies in Lahore, Punjab's provincial capital.