"He threw a backpack on the cashiers desk and demanded she fill it up with cash from the bank," described Jim Amormino, spokesman for the Orange County Sheriff's Department.
The suspect lifted his shirt and pulled out a semiautomatic handgun from his waistband.
"[He] pointed it at the teller who happened to be pregnant, threatened to shoot her and her unborn baby if she did not fill that backpack up with money," Amormino said.
The bank teller handed over an undisclosed amount of cash,
"It's scary to me. I have a baby and I'm here to go to the bank. That's really scary. I can't even imagine what that lady must have felt like," said Laguna Niguel resident Cecilia Richeson.
The robbery was terrifying for some who rarely hear about such violence in this community.
"It's pretty shocking to see a nice neighborhood like this and someone comes and robs a bank inside a store. I shop here," said another Laguna Niguel resident, Brandon Chodosh.
Investigators believe the man is in his 30s, is about 5 feet 9 inches tall and weighs around 180 pounds with an average build. He may be white or Hispanic and has a moustache and goatee and a tattoo on the left side of his neck.
"He was carrying a motorcycle helmet, which points to us he may have driven a motorcycle to the crime scene," said Amormino.
Wells Fargo is offering a $10,000 reward.
Anyone with information about this bank robber should call the Orange County Sheriff's Department at 1-866-847-6273.