I am not a medical professional so don't make serious life decisions based on this or any other post but I've been around life a while (returning to uni for a masters) and have seen a fair share of bleeding.
A few serious questions though as some people want to make jokes, which aren't helpful when you're scared about a medical issue.
1. Was it a large or super solid bowel movement? These can cause some blood vessels in your anus to burst, especially if there was also straining. The TP would be full of blood and the toilet water might look like a massacre happened. (It happens... my workplace is odd so we do sometimes talk about things like this). Although scary, if it's a one-off it's nothing to worry about. Just eat more fibre and drink more water and it should clear up on its own. This is ONLY if the blood was fresh and bright, proper blood-red on your TP.
2. Is the blood is darker, or blackish? Run to the doctor asap. Dark blood is from further up the digestive tract and has been bleeding for a while as it takes time to turn dark. The sooner that is looked at the better.
If it's worrying you a lot or causing stress, there's no harm in getting yourself checked out by a doctor because it's better to have them confirm that you're fine than to ignore it and have it be serious.
More people than will ever admit have had a fresh bloody poo from straining or constipation and been terrified by the toilet result. It usually clears up if it's just a haemorrhoid type.
I hope it's nothing serious!