At about 12:10 a.m., a 30-year-old San Francisco man driving in the 1500 block of Larkin Street saw a woman on her hands and knees in the street, stopped and got out to ask if she needed help, according to police.
The woman said she did need assistance, but when the man tried to help her up, she pushed him away and pointed a handgun at him, police said. She then went through the man's pockets, stole his cell phone, and took money from his wallet before throwing the wallet back at him and running off.
The victim gave chase, but the woman escaped down the block in car being driven by a second suspect.
About 10 minutes later, police spotted a woman matching the robber's description walking several blocks away on Larkin Street near Olive Street.
The victim was able to identify the alleged fraudster, 36-year-old Kimberly Brown, of San Francisco, and she was arrested.
Police weren't able to find the suspect vehicle -- described as a four-door, tan American car -- or the driver.
The gun and the victim's cell phone were also missing, but all the man's money was recovered, police said.
Brown was booked on suspicion of robbery and possession of stolen property.