The incident occurred when three persons, including a woman and a child, were going towards Shahjahanpur from Sitapur and a speeding truck hit their car, police said.
The driver of the car, Shareef (40), and the four-month-old child died on the spot.
The three injured -- Sabir, his wife and one Israr -- were rushed to the district hospital, where their condition was stated to be stable.
The truck driver fled from the spot. Efforts are on to nab him, police said.