Nationalist Congress Party leader Baba Siddique was shot dead in in Mumbai's Bandra East.
The firing took place outside his MLA son Zeeshan Siddiqui's office near Colgate ground in Nirmal Nagar, the official added.
"Two to three rounds were fired. Further probe is underway as teams have rushed to the area," the official said earlier.
Siddiqui had recently joined the NCP from the Congress.