If a person has a damaged blood vessel, then it will most likely spew out blood. Sometimes, if someone gets stabbed, the there is a cut in the skin and in the blood vessel. This would cause someone to bleed a lot. It would take a lot of care to make sure a person is okay.
The person would most likely need to be taken to a hospital for care. Sometimes, a clot will occur and sometimes it occurs in an undamaged blood vessel. If a blood vessel is undamaged and a clot occurs, then that is a serious issue.
The blood then can’t go to reach the organs. If there is a damaged blood vessel that is cut, then eventually the patient would bleed out and then bleed to death.
The flow of blood to tissues beyond the clot may be cut off.
A clot may block the flow of blood to the tissues beyond the clot and cutting off food and oxygen to those tissues. If a clot blocks an artery that nourishes the heart then a heart attack may occur. If a clot blocks an artery to the brain, a stroke may occur.