Police had no suspects after a robber who held up the Citizens Bank branch in Kenmore Square just after noon Thursday escaped with an undetermined amount of cash, Boston police and a witness said Thursday night.

The suspect – described as a 5-foot 9-inch white male in his early 20s – passed a note to a teller demanding money at approximately 12:07 p.m. Thursday. The suspect had a medium build and black hair and was wearing a beige jacket and oval shaped glasses, and he did not appear to be armed, Boston police spokesman David Estrada said. The man fled after the teller handed him an undetermined amount of cash.

“I really didn’t notice anything until he turned and bolted out the door,” said Valerie Ferreira, a junior in the School of Management who was waiting in line behind the robber. Ferreira said she went to the bank to deposit a check and there was only one other customer besides her and the robber.

“I went to the bank and I really didn’t think it was going to get robbed in front of my face,” she said. “The teller directly in front of me was the one getting robbed.”

Ferreira said the teller appeared shaken after the robber fled. After he left, another customer entered before bank security locked the door. When police arrived a few minutes later, Ferreira said, they questioned her, the teller and the other witnesses.

Ferreira added that the man was wearing a winter hat, and she said he was probably caught on camera.

“I can’t imagine this man not being caught,” she said. “There was a camera directly in front of his face.”

Eleven days ago, a Fleet branch at 350 Chestnut Hill Ave. was robbed of $3,200 by a 5-foot 8-inch white man with a thin build and black hair wearing a black hooded coat and a blue knit, according to descriptions in a police report. The suspect in that incident, which occurred around 4:30 p.m., also passed the teller a note demanding money.