The victims' grandmother made the horrific discovery about 9:30 a.m., a Los Angeles Police Department spokesperson told our sister-station KABC.
Each of the children was under the age of 5, authorities said. All were pronounced dead at the scene by Los Angeles firefighter-paramedics.
Investigators were unable to locate the victims' mother, identified as Liliana Carrillo, for several hours.
"At this time we are asking for the public's help in locating a person of interest in this case, a female Hispanic 30 years old," the LAPD said in a tweet, which included Carrillo's name and photo.
"We are receiving reports that she just committed a carjacking in the Bakersfield area" and may be driving in a stolen silver Toyota pickup truck with license No. J258T0, the Police Department said shortly after 1 p.m.
About an hour later, authorities confirmed that 30-year-old Carrillo was taken into custody. Details of her arrest were not immediately available, but police said she is the sole suspect in the case.
"She did a horrific crime here and she followed it up by another crime north of here and it's those behaviors that ultimately got her caught," said Lt. Ben Fernandes.
Investigators are still trying to determine a motive and said they are interviewing family members to find out what lead up to the crime.
"We don't know the background of the family...we're just trying to this puzzle together at this time," said Lt. Anthony Cato.