What explanations does Gertrude offer for Polonius murder?

In Shakespeare's play "Hamlet," Gertrude does not offer any explanations for Polonius's murder. In the play, Hamlet mistaking Polonius for the eavesdropping King Claudius, stabs him to death behind the arras in Gertrude's chamber. It is Hamlet who later explains the murder to Gertrude in Act III, Scene IV, but Gertrude herself does not offer any explanations for the incident.