The accident happened on Pracha Samrarn Road in front of Soi Pracha Samrarn 3, a little past midnight.
Police said said Nirut Kulkerd, 38, died on the spot. Jiraporn Boonkaew, 51, and Printip Pasitkosin, 8, died at the Nong Chok Hospital.
The four injured were identified as Adisak Sakwichit, 37, Warunee Sakwichit 36, Naruemol Khamkhun 22, and Piramet Pasitkosin, 5.
Pol Capt Suwit Ratachaipat of Nong Chok Police Station said the survivors would be interrogated after their condition improves to find out who had driven the car.