CLAREMONT (CNS / FOX 11) - A 14-year-old boy was in custody Thursday on suspicion of stabbing his older sister to death in Claremont.
The assault occurred as the two were alone at a residence in the 300 block of Andover Drive around 5 p.m. Wednesday, said Claremont police Detective Lt. Mike Ciszek.
Aspen Geurts, 15, died at the scene, said coroner's Assistant Chief Ed Winter.
The suspect was apprehended with the murder weapon, a knife, in his possession, as he walked away from the residence, Ciszek said, adding that the boy was "calm and cooperative with officers during the investigation.''
Police officers and Los Angeles County Fire Department paramedics responded to the scene as the result of a cellphone call taken by the California Highway Patrol at 5:07 p.m., Ciszek said.
Ciszek would not identify who made the emergency call. The suspect was transferred to the Los Padrinos Juvenile Hall in Pomona, Ciszek said.
Authorities did not immediately say what prompted the stabbing, which Ciszek said was the first homicide in Claremont since October 2009.