A man entered the victim's home in the 700 block of Bridge Road shortly before 5:30 p.m., brandished a knife and sexually assaulted her, police said.
After the assault, the suspect ran away in an unknown direction. The suspect was described as a Hispanic man with an accent, between 20 and 30 years old, about 5 feet 5 inches tall, with a medium build.
Police believe the victim may have been targeted and it appears to have been an isolated incident.
Anyone with information regarding the attack is asked to call San Leandro police Detective Ali Khan at (510) 3243.