Hurt has a wider, more general meaning. Injured is usually more specific. In your example, I would choose 'injured' because it is very naturally paired with 'seriously' when describing physical damage to a persons body in an accident.
'hurt' can also refer to physical damage, but it can be used for other types of pain, like emotional hurt or mental trauma too. Although I have heard 'mental injury', the word injury most naturally implies physical wounds on the body.