Disturbing video has emerged of killer whales off the coast of Monterey Bay in California behaving in a most gruesome fashion in front of a whale-watching group, and it’s part of a killing frenzy the mammals have engaged in in the area in the past week or so. The orcas were cause on video tearing apart a baby grey whale calf right in front of its mother. The video from the incident is embedded at the bottom of this post.

It’s the fourth kill in the last few days in the region, a spree that scientists say is unprecedented. This time, it happened to occur in front of a whale-watching group, who got to see Mother Nature at its most violent right up close. Although it typically takes hours to kill a grey whale calf because the mother uses its powerful tail to beat off attackers, the pod of nine killer whales took only 20 minutes to dispatch their prey. The whales appeared to be much thinner than normal, so they may have been too weak to put up a fight.

“This has never happened in my thirty years,” Nancy Black, a marine biologist with Monterey Bay Whale Watch, told The San Francisco Chronicle. “Just to witness that out in nature when you usually see that kind of thing on television is really spectacular.”