Final answer:
Alfred thought that Jackson might be seriously injured or dead after he fell down and stayed down.
Step-by-step explanation:
When Jackson fell down and stayed down, Alfred thought that he might be seriously injured or even dead. This assumption is based on the fact that Jackson fell after being shot and blood was seen dripping from his wound. Alfred's concern for Jackson's condition is a natural reaction because falling down and staying down is usually a sign of being unable to get up due to injury or unconsciousness.