Condolences poured in as news broke that former MQM leader Syed Ali Raza Abidi has been shot dead in Karachi.
Prime minister Imran Khan, according to his party's Twitter account, expressed his sorrow at Abidi's murder and sought an immediate report.
Former MQM convener Farooq Sattar said "Abidi was like my children", adding that "we had raised him with our own hands, he was Pakistan's future. With what cowardice and coldness he was targeted and martyred".
Former MQM Rabita Committee member Wasay Jalil remembered Abidi as his "best colleague" and a gem of a person.
President Arif Alvi condemned Abidi's death and prayed for his loved ones.
PML-N leader Ahsan Iqbal termed Abidi's death a "terrible tragedy", adding that "violence in politics is an unforgivable crime."
Nadeem Nusrat, one of MQM founder Altaf Hussain's allies, described Abidi's death as a tragedy of tragedies.
PPP leader Dr Nafisa Shah remember Abidi as one of MQM's brightest faces, and wondered "who could be so cruel to take the life of a young and promising leader?"
Senator Rehman Malik urged Sindh IGP to "ensure the arrest of the culprits".
Minister of State for Parliamentary Affairs Ali Muhammad Khan "condemned the killing" and demanded that the "killers must be apprehended".
PPP Senator Saeed Ghani regretted Abidi's untimely demise and claimed that he "was about to join PPP before GE 2018".
PML-N leader Abid Sher Ali prayed that Abidi's family gets the courage to "bear this irreparable loss".
ANP leader Afrasiab Khattak said: "Abidi always raised his voice in the parliament with bravery and courage. He opposed oppression in every part of the country. Abidi bhai will always be remembered for his bold stances."
Shahzad Akbar, the Special Assistant to Prime Minister on Accountability, was "deeply saddened" on Abidi's murder.