Around 9:10 p.m., a woman at home with her young children in the 100 block of Laverne Avenue was startled when her house's alarm system sound, Marin County sheriff's officials said.
Believing the heavy winds and rain may have triggered the alarm, the woman walked downstairs to investigate and came face-to-face with an intruder, according to the sheriff's office.
The burglar immediately fled out of the back of the home and the woman ran upstairs to her children and called 911.
Sheriff's deputies were joined by Mill Valley police officers and a Novato police K-9 to search the area for the burglar, but no suspects were found.
Deputies learned that the burglar had forced entry into the house by smashing a locked rear glass door.
Sheriff's officials say the break-in is the latest of several home invasion robberies and burglaries throughout the county and the Bay Area over the past several weeks in which homeowners have been startled to find intruders in their homes.
In two recent home invasion robberies in Oakland, intruders broke into homes and shot elderly homeowners.
On Friday afternoon, a woman believed to be in her 70s was shot and killed in an apparent home invasion robbery in Oakland's Fruitvale District, according to police.
"Although all residential burglaries raise fears and concerns in the local communities where they occur, a burglar who strikes so brazenly during the night while the residents are home raises these fears to a whole different level," Marin County sheriff's officials said in a statement.
The sheriff's office has recently launched special operations countywide in response to these types of crimes, officials said.
An investigation into the Mill Valley home invasion is ongoing and anyone with information about the case is asked to call the Marin County Sheriff's Office at (415) 473-7265 or Bay Area Crime Stoppers at (800) 222-TIPS.