The mishap occurred near Lingala village under Vatsavai mandal last night when a family, including a couple and their two sons, were heading towards Vatsavai village on their motorcycle, they said.
While they were travelling on the Muneru Kazway bridge, a speeding bike coming from the opposite direction suddenly hit their motorcycle.
Two persons, including a six-month-old boy, died on the spot in the mishap while one person later succumbed to injuries in hospital, police sub-inspector K Sathish said.
The three injured were admitted to Jaggaiahpet Government Hospital, where their condition was reported to be out of danger, police said.
A case has been registered in this regard and further investigation is on, the SI said.