YONKERS, Westchester County (WABC) -- It was a tragic start to Labor Day for the family of Zachary Dunn of Yonkers.[br /][br /]The 18-year-old's car broke down about 2:50 Monday morning on the Northbound lanes of the Saw Mill River Parkway, just north of the Bronx county line. For reasons that are still unclear, the teenager never pulled his car completely off the parkway. Moments later, another car, an Acura TSX, slammed into the back of the vehicle and critically injured Dunn.[br /][Ads /][br /][twitter ID="[br /]772817568545529856" /][br /][br /]First responders rushed Dunn to Jacobi Medical Center in the Bronx, but his injuries were too severe. At 9:30 a.m. Dunn died at the hospital. His passenger, who remains unidentified was taken to St. Joseph's Medical Center with non-life threatening injuries.[br /][Ads /][br /]Investigators at the scene wanted to speak to the driver of the Acura, but he or she took off before police arrived. Authorities say the hit-and-run driver abandoned the Acura at the accident scene, and got into another vehicle - apparently another Acura TSX, and fled north on the Parkway. Investigators say the getaway car was either grey or blue in color and had temporary New Jersey license plates.[br /][br /]Furthermore, police believe all the people in the two Acuras knew each other. They don't believe Dunn was connected to them in any way.[br /][br /]Dunn was just one day away from starting school at Westchester Community College. It was supposed to be just the beginning of chasing his dreams. Instead, his family is now forced to make funeral arrangements.[br /][br /]He had graduated from Palisade Prep in June.