Having witnessed three fatal officer involved shootings and covered several hundred homicides (and who knows how many more non-fatal shootings and stabbings) I can attest that even with wounds that ultimately proved fatal, lots of people can and do go on for some time after the initial wound(s). I have seen them run several blocks, drive several miles and even engage in rational-sounding conversations for a time with visible brain matter coming out of their heads. It's really quite rare for anyone to fall down instantly dead after being shot or stabbed, and fairly common for them to get back up one or more times after suffering apparently fatal wounds. That is especially true with suspects, as many are, who are under the influence of various drugs or booze. The human body is pretty tough.