Police say the suspect targeted houses while residents are at home, in one case walking right in through the front door as the victim slept.
"It's scary," said Arcadia resident Martin Dessoffy. "Makes you think you should be sleeping with a gun at your side every night."
The first burglary occurred Tuesday morning just before 5 a.m. in the 100 block of Diamond Street. The female victim woke to find the suspect with a flashlight in her bedroom.
Police say he grabbed the woman's purse at the foot of the bed and ran out of the house. Neither the woman nor the two teenage children who were home were hurt.
Investigators say the thief got in through the unlocked front door.
"We want to make sure the public is vigilant," said Arcadia Police Lt. Bob Anderson. "Lock doors and windows, set alarms if they have them, and call with any information that appears to be suspicious around their homes."
Police say the suspect tried to strike again Wednesday night around 11 p.m. in the 600 block of West Walnut Avenue.
A resident heard someone trying to open the front door, and then moments later the side door. The homeowner turned on an outside light and saw the suspect at the door.
The would-be thief shined his flashlight in the man's face and took off.
"It makes you a little nervous especially in the summer," said Arcadia resident Chris Amenson. "When you want to sleep with windows open, want to feel relaxed and safe. But not if someone is coming in when you are there."
Anyone with information is urged to call the Arcadia Police Department at 626-574-5150.