Warning: Some may find this story and the attached image disturbing.

The mystery of what drove more than 40 birds to plummet from the sky earlier this month has been solved, according to federal wildlife officials.

A flock of starlings had been fleeing a larger bird when they dove toward the pavement near the BC Ferries terminal in Tsawwassen, B.C. on Sept. 14.

The Canadian Wildlife Service said the cloud of birds swooped then pulled back up, but those at the tail end of the flock were unable to pull out of the dive in time. Of the approximately 200 European starlings that collided with the ground, 42 died on impact.

A veterinary pathologist conducted a necropsy to figure out cause of death, and concluded that the juvenile birds died of compressive chest injury.

"No evidence of underlying infectious disease or intoxication has been found," an Environment and Climate Change Canada spokesperson said in an email to CTV News.

"European starlings can form very large flocks and execute amazing swooping and whirling patterns – called a murmuration – to avoid a predatory bird."

This murmuration, which resulted in mass death, was witnessed by Kevin Beech, who'd been driving through the area at the time.

Beech told CTV News he noticed the first bird strike the ground, then saw dozens follow suit.

"It was really creepy," he said at the time.

And it appears that more birds have died in a similar manner. When CTV visited the area last week, several more birds were seen dead on the ground.

With files from CTV Vancouver's Michele Brunoro