When they were both found in the crosswalk, the teen had sustained leg injuries, while the 15-month-old child was "pulseless and not breathing."
After taking his baby boy off life support, the sports star took to Facebook to remember his sweet son. The athlete shared this family photo (above), captioning it:
"I want to thank everyone who has been there for us, in all forms and shapes. Thoughts, prayers, in person - whatever. We've received 100s and 100s of txt messages, emails, fb messages, etc - we are blown away. Your support means the world to us.
About an hour ago, our baby was declared brain dead. He tried to fight so hard. He even died at one point but they brought him back. He's a little fighter. His heart is still beating but his brain is no longer working.
Our hearts are broken and there's a void in my soul but we will get through this.
Again, your support means the world and I wish we could respond to each and every one of you but right now, we are going work through this.
Funeral arrangements will be posted here.
RIP Liam Mikael Kowal. 5/25/2015-9/4/2016"
Authorities say the driver, Donna Marie Higgins, tried to take off after the accident, but onlookers were able to follow her and ultimately stop her until the cops showed up.
Police say she failed a field sobriety test, and arrested her for felony hit-and-run and felony drunk driving. You can see her mugshot (below):
The fighter revealed on his son's GoFundMepage that he will be donating Liam's organs, writing:
"This isn't easy to write but Liam is going to donate his organs, so that his little heart can make another child live and another set of parents not have to go through what we have to. We were told that we can donate to someone we know. Therefore, I am writing this post to ask if there is a child out there we know that needs a heart or any other organ.
It hurts to write this but Liam loved to share and the person we were going to raise him to be would love to help someone else. So anyone we know, or someone you know, inbox me please."
Our hearts are with everyone affected by the devastating loss.