Authorities identified the woman as 41-year-old Cecilia Meza and 17-year-old Kelsey Meza.
Monrovia police responded to an apartment building Wednesday following a report of an assault taking place at an apartment on the 800 block of West Colorado Boulevard at approximately 1:30 p.m.
Late Wednesday, authorities identified Nimrod Perez Guerrero, 33, as a suspect wanted in the double murder. Guerrero should be considered armed and dangerous.
Guerrero is described as Hispanic, with brown hair, brown eyes, weighing 200 pounds and 5 feet, 8 inches tall.
He may possibly be driving a gray 2014 Toyota RAV4 with a California license plate of 7FPB132.
Detectives believe the suspect lived in the apartment with Meza and her daughter, but they aren't revealing his relationship with either victim.
Kelsey was a student at Monrovia High School, located across the street from where she lived. Monrovia Unified School District leaders confirmed the death of one of their students, saying the entire community is mourning the loss.
"We are all mourning tonight because of the loss of one of our Monrovia High School students," said School Superintendent Kathy Thorosian in a statement. "There is no question that a tragedy of this nature affects our entire community. It is difficult to process the death of anyone, much less someone so young and so promising. The District will have grief counselors available on campus to support students and staff as we all grapple with this terrible loss."
Homicide detectives from the Los Angeles County Sheriff's Department are assisting Monrovia police in the investigation.
Anyone with information about this incident is encouraged to contact the Los Angeles County Sheriff's Department's Homicide Bureau at (323) 890-5500.