Norma Demerchant remains in serious condition in the intensive care unit at Harborview Medical Center in Seattle, hospital spokeswoman Susan Gregg said Monday morning.

Demerchant and her husband Paul were attacked by their son Sean P. Demerchant late Sunday night at their home in Freeland.

The Island County Sheriff’s Office said Sean Demerchant stabbed his parents, but declined to immediately release further details. Sheriff Mark Brown said the investigation into the attack is ongoing.

Demerchant was arrested late Sunday and remains in custody in the Island County jail in Coupeville.

Demerchant is expected to make his first court appearance this afternoon in Island County Superior Court.