Four-year-old Ronan Kerr died in July, a week after part of a eucalyptus tree fell on him while he was playing at Villa La Jolla Park.

“He was literally everything to me,” said his father, Cathal Kerr. “I can’t describe how much I ache and pain. I feel like a part of my body has been taken from me and, like, missing a limb.”

Ronan was the air his parents breathed. His parents also describe the 4-year-old as a bright light that would one day change the world.

“Every child will make their impact in their own way, but you just felt like he was destined to make a really big impact,” said his mother, Dara Kerr.

Video of Ronan and his brother shows them baton fighting with each other about five minutes before attorneys say a 34-foot-long eucalyptus branch came crashing down onto Ronan and his dad.

A piece of what attorneys say was a 34-foot-long eucalyptus branch that came crashing down onto Ronan Kerr and his father.

A piece of what attorneys say was a 34-foot-long eucalyptus branch that came crashing down onto Ronan Kerr and his father.

“All of a sudden, I just heard a crack, and I heard people screaming,” Cathal said. “Instinctually, I pushed my older son and another girl out of the way, and then went to put my hands around Ronan, and the next thing I remember is waking up on the ground next to him.”

Cathal showed NBC 7 pictures of his bloodied and bruised face after shielding his son from the tree.

He says doctors tell him he’s suffered lifelong damage to parts of his body, including his leg that now limits what he can do with his 7-year-old son. That’s part of the reason why the Kerr family has filed a complaint against the city of San Diego and its arborist doing business as Atlas Tree Service.

“We want there to be awareness around the situation and such that no other family needs to go through this, needs to go through the pain what we’re going through,” Ronan’s mom said.

The complaint lists more than 30 incidents since 1983 involving eucalyptus trees, often called windowmakers. One high-profile case involved a 4-year-old hit and killed near the entrance of the San Diego Zoo back in 1983. In 2013, a woman was injured by a tree in Mission Bay Park. The complaint also lists the eucalyptus tree that fell and smashed four cars on UC San Diego’s campus in 2017.

“If we can avoid another family for going through this kind of loss, it’ll be worth it, and Ronan would really be so proud of us out there for keeping his name alive by doing that,” Cathal said.

Ronan would’ve celebrated his 5th birthday on Dec. 2. His family is hoping to start a foundation to bring attention to the issue and help others.

Typically, the city of San Diego doesn’t comment on pending litigation. NBC 7 received an auto-response because of the holiday. Our calls to the arborist were not returned.

In addition to financial damages, the lawsuit requests that all potentially dangerous eucalyptus trees near parks and schools be removed or better managed.