So it seems yet another crime suspect has been taught the ultimate lesson that one never knows who is carrying a gun.
Harris County Sheriff's deputies told KTRK-TV that a driver was exiting his car early Tuesday morning in Houston when he was approached by two men.
And this duo tried to rob him, deputies told the station.
A KTRK reporter noted in a video tweet that the "intended victim ... had his own weapon" and fatally shot one of the suspects in an "exchange of gunfire."
"It appears he is aware, and that's why he was ready with his own firearm," Ruben Martinez with the sheriff's office added to the station.
Deputies also told KTRK the victim was shot in the leg and went to a hospital but is expected to be OK.
What about the other suspect?
Deputies are looking for the second suspect who got away, the station said
The sheriff's office on Tuesday told TheBlaze it had no way of confirming if the victim is a licensed handgun carrier; the sheriff's office did not offer TheBlaze an update on the whereabouts of the second suspect.
This story has been updated.