Two teens were reportedly arrested hours apart Wednesday in connection with the murder of a Pennsylvania high school track star, who was gunned down outside his home just days before he was set to start classes at Penn State University on a full-ride scholarship.

Byron Vinson, 15, and Taron Small, 16, were both charged with murder and criminal conspiracy in the death of 18-year-old Kristian Marche.

Marche was shot to death outside his home Aug. 13 in what police initially called a "targeted attack."

Police said Marche heard people trying to break into his family’s home that day and twice encountered the teens as he investigated the noises. Marche turned his back to the pair and began walking away when Small allegedly fired the fatal shot, officials said.

Marche was struck in the head and died at a local hospital less than a day later.

Homicide Lt. Norman Davenport told FOX29 there was “some acquaintance” between Marche and the suspect, but the nature of the relationship was unclear.

Marche, a runner at Imhotep Charter School and a wide receiver for its football team, had been scheduled to leave for State College, Penn., the day after the shooting.

The university said Marche finished second in the 100-meter dash at the 2017 Pennsylvania Interscholastic Athletic Association state championships, third in 2016 and fourth in 2018.

One of Marche’s coaches, Jerome Lowery, described him as "always a loving person.”

“One of the first things he would do when he would come home was look for his mom and ask her how her day was,” Lowery told the running news website PennTrackXC.

A GoFundMe page has been set up as a scholarship fund in Marche’s name.

Fox News’ Greg Norman and the Associated Press contributed to this report.