SAN DIEGO -- A Carmel Valley woman was tied up and threatened with a knife Tuesday by a man who accosted her as she arrived home, police said.

The 47-year-old victim was pulling into her garage about 11 a.m. in the 10500 block of Whispering Hills Lane when she spotted the suspect on the sidewalk, according to San Diego police spokeswoman Monica Munoz.

The woman activated her automatic garage door, but the man got inside before the door closed, Munoz said.

The victim, whose name was withheld, told investigators that her attacker tied her up at knifepoint, took her car keys and demanded the house alarm code when the alarm activated, but apparently got frustrated and ran off.

The attacker was described as white, 25 to 30 years old, 5 feet 5 inches tall with a thin build and short hair. He was wearing a baseball cap, light gray zippered sweatshirt and blue jeans, Munoz said.