It seems impossible, but some beautiful swans are responsible for a man's death.
INSIDE EDITION spoke to the devastated family of 37-year-old Tony Hensley who was killed by the creatures that have come to symbolize peace and tranquility.
Hensley was in a kayak checking a swan nest in a pond at an apartment complex outside Chicago.
Hensley's father told INSIDE EDITION, "They kept attacking him. He almost made it back to shore but they kept attacking him."
"They're very big and very beautiful animals. They're very large, and very protective animals," said Hensley's brother.
You'd be surprised at how aggressive swans can be. YouTube videos show them fighting with geese, their natural enemies. Swans are big birds that weigh over 30 pounds, with an imposing eight-foot wingspan.
In one video, a swan attacked a dog swimming in the water, while another swan chases a dog onshore.
Humans can also be a target. Video caught one enraged swan terrorizing fishermen in a small boat, while another swan attacked two people in a kayak.
A kayak was what Tony Hensley was in when the swans went after him, knocking him into the water.
"When you get hit it's like someone punching you because they're so powerful," said the father.
Hensley was quite familiar with the swans. He was their caretaker, working for a company that supplies swans to keep away Canadian geese from making a mess in residential neighborhoods.
Police say Hensley couldn't escape the swans and suffered hypothermia in the 38-degree water and drowned.
Bird expert Dr. Laurie Hess told INSIDE EDITION, "The swan was probably protecting his nest site, his babies."
Hess calls this a freak accident and says the presence of the caretaker's kayak may have contributed to the swans aggressive behavior.
"It could have been the kayak. It could have been the person. It could have been anything that was in the water that is large and maybe threatening," said Hess.
Tony Hensley leaves behind a grieving wife and two young daughters. No one can believe he died while taking care of one of the world's most beautiful birds.
Hensley's brother said, "He was doing what he loved to do."
The family has set up the Anthony Hensley Memorial Children's Fund. Donations can be sent to 7 E Park Blvd. Villa Park, IL. 60181.