A 45-year-old school bus driver was killed allegedly by the vehicle's helper following a quarrel over borrowing a phone on Saturday, police said.
The incident was reported from Netaji Subhash Place in northwest Delhi, the police said, adding that the deceased was identified as Joginder.
The police were informed at around 11.20 am about the incident.
The victim had asked the accused, identified as Chooda Maniaryal, to lend him his phone on Saturday but the latter refused, following which a quarrel ensued between the two men, said Aslam Khan, the Deputy Commissioner of Police (northwest).
Maniaryal (23) allegedly hit on the driver's head with a fire extinguisher, leading to his death, he added.