LOS ANGELES—Authorities have identified the three young children who were killed in a gruesome slaying in Los Angeles over the weekend. Their mother is the suspect in their deaths and in custody Monday. The autopsies of 3-year-old Joanna Denton Carrillo, her 2-year-old brother, Terry, and 6-month-old sister, Sierra, were pending on Monday, coroner’s records said. Their mother, Liliana Carrillo, was held in Kern County on Monday afternoon on carjacking-related charges as Los Angeles authorities planned to seek her extradition. A memorial of photographs, candles, flowers and balloons grew outside the apartment complex Monday, days after the children’s grandmother returned home from work Saturday morning and found their bodies in their apartment in the San Fernando Valley neighborhood of Reseda. A GoFundMe fundraiser for the father had garnered more than $30,000 in donations by Monday afternoon. Police have not disclosed a motive or how the children were killed. The Los Angeles …