St. Louis, MO (AP)  Authorities say an off-duty deputy shot and killed a suspected carjacker after he struck a 67-year-old man as he walked on a suburban St. Louis sidewalk with his 10-year-old grandson. St. Louis County police spokeswoman Tracy Panus said the suspect used a weapon to steal the truck from the 67-year-old at a McDonalds restaurant before making a U-Turn, veering into the sidewalk and hitting him. The St. Louis Post-Dispatch reports that the deputy saw what happened while headed to his job at the courthouse dressed in his uniform. Sheriff Vernon Betts said the deputy fired his weapon while chasing after the man.