Philadelphia police say the men were street sweeping the Shop Rite parking lot on the 6300 block of Oxford Avenue around 3 a.m. Saturday.
Investigators say the men began yelling at each other from their trucks.
A short time later, police say the two left their trucks and continued arguing with each other.
That's when, according to police, one of the men pulled out a gun, shooting the other in the chest.
The victim, a 44-year-old-man, died at the scene.
Police say the suspect remained on the scene and is in custody.