An argument in a Toyota on Rossville Boulevard near Roy's Grill on Thursday morning led to a bloody assault and halted traffic.
Police said passenger David Leflie of Madisonville, Tn., slashed his own throat as well as stabbing the driver, Jason Gourley, with a four-inch switchblade. The driver had serious cuts on his face and arm.
A laser had to be used to restrain Leflie after a number of officers arrived.
Both men were taken to Erlanger Hospital.
The incident happened around 8 a.m.