South Gate police responded to a robbery in progress at a Bank of America in the 4400 block of Tweedy Boulevard at about 8:23 a.m.
Police say they interrupted the robbery of an armored truck and rescued armored transport employees without injury.
When officers arrived, police say several suspect fled the scene.
Streets were shut down while police and SWAT officers in full tactical gear - with weapons drawn - surrounded and searched the armored vehicle.
The bank was not open at the time.
Witnesses say police arrested one suspect.
The investigation is ongoing.