Senior lawyer Khawaja Shamsul Islam was killed in the Karachi defense area on Friday, police said.
The son of the lawyer Daniyal, was also injured in the attack and was transferred to the hospital with his father, who died of his injuries, confirmed the police.
The incident took place in a mosque of phase VI of the DHA where Islam had gone to attend the funeral prayers of the Muzzammil merchant.
Unidentified armed men opened fire during the funeral, seriously injuring the father and the son, the police said, adding that an additional investigation was underway.
Taking note of the murder, the Minister of the Interior of the Sindh, Ziaul Hassan Lanjar, ordered SSP South to submit a detailed report on the initial police measures taken following the incident.
He also asked police teams to mobilize for the immediate arrest of the suspects involved in the shooting and looked for updates from minute to minute.