Harrison has yet to be arrested or charged with the crime.
"I just walked off the practice field [at rookie minicamp] and heard about the incident, and that's all I know," Colts coach Tony Dungy said Friday. "We're obviously going to look into it. I haven't spoken to Marvin yet."
Calls by ESPN to Harrison and his agent have not been returned.
The source said the alleged victim came into the bar, Playmakers, around 5 p.m. and engaged in an argument with Harrison, who was at the bar. The victim then left the bar, heading to his car, with Harrison following. Gunfire broke out, the victim was hit in the hand, and a young girl was slightly injured by flying glass from a car that apparently was hit by a bullet.
Police came to scene, but the victim did not identify a shooter. On Wednesday, according to the source, ballistic tests showed that the gun that had fired the shots was a custom-made Belgian weapon, and police determined that Harrison owned such a gun.
Police then went to a Philadelphia car wash owned by Harrison to question him about the gun. Harrison admitted owning such a weapon, but claimed it never left his suburban Philadelphia home.
However, the source said the gun was discovered in a bucket at the car wash, and tests showed that it had fired seven bullets that matched those found at the scene.
The source said police were contacted Friday by an attorney representing a second alleged victim in the shooting, and police are now waiting for that individual to come forward.