SAN DIEGO -- The San Diego Police Department is investigating a home invasion and sexual assault that happened this week, 10News reported.

According to news release from the SDPD, the incident occurred Tuesday at about 11:30 a.m., in the 6500 block of Reflection Drive.

The incident is believed to be the sixth case in a series that began in June 2008 in the College area, police said.

Police said on Tuesday a woman had just returned from a shopping trip with her 18-month-old child and entered her home. She retrieved items from her vehicle and was grabbed from behind by an unknown male. The man threatened her with a knife, demanded cash and then sexually assaulted the woman.

The man left the scene, and the victim took her child to seek help, police said.

The attacker is described as a white or Latino male, approximately 30 years old, 5 feet 6 inches tall with a medium build. He was wearing a black jacket, denim jeans and black shoes.

Police said Tuesday's attack is similar to a series of cases that began last year, with the attacker accosting women shortly after they return home. The attacker enters through an open garage or front door, generally while the victim is carrying items into the home. The attacker demands cash and either threatens a sexual assault or commits a sexual assault.

All the victims are Asian women, between ages 20 and 48, police said.

Anyone with information regarding this case or the series is asked to contact the SDPD at 619-531-2299, the UCSD Police Department at 858-534-4358 or Crime Stoppers' anonymous tip line at 888-580-8477.