A student of Kerala Public School, Javed Hussain, was rushed to Tata Main Hospital, the police said.
Javed, who was studying while his two brothers were sleeping in a room, rushed to open the door on hearing knocks at the door at midnight.
The accused persons enquired about Javed's father Md. Aslam, a bangle wholesaler, and opened fire as soon as Javed replied in affirmation, the police said.
Superintendent of Police (City) Karthik S said the involvement of one Chotu Bachha was being suspected in the incident over an old enmity.