I've never heard of Panic In Year Zero! (a.k.a. End of the World), a 1962 science fiction movie starring Ray Milland about a family that survives a nuclear explosion in Los Angeles. It was just uploaded to the Internet Archive and I've got it bookmarked to watch later. The jazz soundtrack at the beginning is great!
Harry Baldwin (Ray Milland), his wife Ann (Jean Hagen), their son Rick (Frankie Avalon), and daughter Karen (Mary Mitchel) leave suburban Los Angeles on a camping trip in the Sierra Nevada just after sunrise. After driving for two hours, the Baldwins notice unusually bright light flashes coming from a great distance behind them. Sporadic news reports broadcast on CONELRAD hint at the start of an atomic war, later confirmed when the Baldwins see a large mushroom cloud over what was Los Angeles. The family initially attempts to return to rescue Ann's mother back at their home, but they soon abandon the plan as panicked people climb over one another to escape the fallout from multiple nuclear explosions. Witnessing society being torn apart, Harry decides that the family must find refuge at their secluded vacation spot.
The Baldwins stop to buy supplies at a small town off the main road, which has not yet been inundated by the crowd fleeing Los Angeles. When Harry attempts buy tools and guns from hardware store owner Ed Johnson (Richard Garland), who believes only Los Angeles has been hit, and assumes the government will remain intact, withholds the guns per state law since Harry can only cover them with checks. With Rick's help, Harry absconds with the weapons, but insists to Johnson that he will eventually return to pay for them in full. On the road, the family encounters three threatening young hoodlums, Carl (Richard Bakalyan), Mickey (Rex Holman), and Andy (Neil Nephew), but manage to drive them off.
I don't want to read the rest.