The three-vehicle crash was reported at about 2:45 a.m.
It took place near the I-285 interchange when a vehicle with mechanical problems had stalled in the roadway and was being pushed when the crash took place.
The westbound lanes of I-20 were shut for five hours.
Apart from the three killed, one person was critically injured and was admitted to hospital while three others had minor injuries and were treated at the scene.
The eastbound lanes resumed by 5:30 a.m., and westbound traffic was resumed at 7:40 a.m.