Being attacked by a hungry shark or being chased by an unruly mob on the streets can be described as harrowing, which means "provoking feelings of fear or horror."
The adjective harrowing is often used to describe a firsthand experience that is terrifying, such as a harrowing drive home in icy weather, but it can also refer to a secondhand experience, such as reading or watching something that is very frightening or disturbing. If you read someone’s account of being shipwrecked in Antarctica, you might describe that as a harrowing story. A harrowing experience typically unfolds over a period of time. For example, if you bump into a shark while swimming, that’s merely scary. If the shark attacks you, then it becomes a harrowing ordeal.