Delaware State Police are calling it an extreme case of road rage.
This mother saying an irate 55 to 60-year-old man got out of his vehicle and completely lost control of his temper after the teen made the mistake of cutting the driver off.
"She said, 'may I help you?' He said, 'are you trying to kill me?'," the mother said.
"She had opened her window just enough to converse with this guy, but it is open enough, where he was able to reach in with a knife and to put up to her throat. He threatened to kill her. At one point, he punched her in the face, and rolled the window the rest of the way down," Cpl. Jeffrey Whitmarsh of the Delaware State Police said.
The mother said he held the knife to her daughter's throat, tried to get the keys out of the ignition, ripped the key out of the ignition, and broke the key in half.
Police say the irate driver took off in a blue or black late model pickup truck only after other drivers approached and rendered aid to the bleeding, frightened teenager.
Delaware State Police suspect the driver knew his way around the back roads and may live in the area. They're hoping someone turns him in because his next case of road rage may be much worse.
Click here to get the latest Philadelphia news and headlines from across the Delaware and Lehigh valleys.