The First Volunteer Bank location on Highway 58 was robbed Wednesday morning.
Chattanooga police said a man with a dark ball cap passed a note to a teller demanding cash.
She reached to get the cash and another person walked into the bank. The robber put his hands in his pockets. It's unclear if he actually had a weapon.
No one inside the bank was injured.
The robber walked out a door on the north side at about 10:15 a.m. and ran to the rear of the brick building.
He may have jumped the chain link fence at the edge of the property.
"We don't know how much money he's got right now," said Chattanooga Police Officer Tim McFarland, who was at the scene.
The man didn't wear gloves or a mask. He appeared to be in his 40s or 50s, with a heavyset build.
FBI data shows that most bank robberies take place in the South. Notes are the most common way to rob a bank and most robberies occur between 9 a.m. and 11 a.m.
The bank robbery at the 4757 Highway 58 bank branch comes one day after the Family Dollar store next door was robbed.
At about 8 a.m. Tuesday, two men wearing gloves and masks and armed with guns entered the store, forcing a truck driver inside. A mother and child began to enter the store but turned away.
The robbers fled without taking any money. No one was injured. Police are also searching information in that case.
Anyone with information about the robberies is asked to phone Chattanooga police at 423-698-2525 or make a confidential call to Crime Stoppers at 423-698-3333.
Contact staff writer Beth Burger at email@example.com or 423-757-6406. Follow her on Twitter at twitter.com/abburger.