User blog comment:John Alfred Hammond, CEO/Total list of Jurassic Park Victims.../@comment-86.133.28.53-20130621193611

Before Arnold and Wu are killed, the first indication that the Raptor's got out is a random scream coming from outside. This was probably a gardener of maintenance worker. Perhaps its the guy who tells Grant, Sattler, Malcolm and Tim about how the Raptors attack the fences when they first see them in the book.