UPDATED Sept. 15, 7:11 a.m.
Police say the man arrested in the killing of three children inside a West Sacramento apartment was the children's father.
Robert Hodges, 33, was taken into custody after midnight.
Police say neighbors called 911 to report a domestic violence incident involving Hodges and his wife, and that as officers were on their way a second call came in reporting the killings.
West Sacramento Police Sgt. Roger Kinney says the mother did not witness the killings but that "she was in close proximity."
Hodges' grandmother, Irene Aiello, tells The Associated Press that relatives were unaware of any previous marital disputes.
Aiello says the couple had been married more than a dozen years and had an 11-year-old boy, a 9-year-old girl and another boy, born in January.
West Sacramento Mayor Christopher Cabaldon issued a statement saying he was shocked by the tragedy.
“In a small town, each of us, whether parents, neighbors, mentors, and just plain citizens, know that protecting our children is our most sacred duty, and the betrayal of that duty in the home is unfathomable and unconscionable," Cabaldon wrote.
Hundreds of people gathered at a vigil for the children Thursday night, leaving candles, stuffed animals and signed cards in their honor.
Hodges is being held without bail for a Monday court appearance, with charges likely to be announced that morning.
Autopsies that could show how the children were killed are expected to be released Friday.
The Associated Press contributed to this report