A 70-year-old man was killed during a fight over honking at Tilak Nagar in Mumbai's Chembur area on Thursday, police said.
The incident took place around noon.
Deepak Chawariya , 29 and his brother Manoj, 32 were leaving for work on a motorcycle when Sandeep Parcha, 28 and his father Palsingh, 70 allegedly abused them for honking, police said.
Deepak and Manoj confronted them, which led to a heated argument.
Hearing the commotion, Deepak and Manoj's father Manohar, 70 and their sister Pooja came out of the house and intervened, trying to calm down both the sides.
Sandeep, however, allegedly attacked them with a knife, a police official said.
Manohar sustained severe injuries and died at a hospital.
Deepak, Manoj and Pooja were injured in the attack.
No arrest had been made yet, the police official said, adding that probe was on.