Mu math…
Think logically.
The human body contains 1.2 to 1.5 gallons of blood.
For 49 people, that's 58.8 to 73.5 gallons. Let's assume 10% of that would be spilled in a massacre like what has been alleged in NZ… That's 5.8 to 7.3 gallons. Fill a five gallon bucket with red paint and start splashing it around… 5 gallons of paint will cover 350 square feet.
There should be a lot of blood at the scene.