How long ago was this? Soviet missiles were extremely inaccurate for a long time, so there's the definite possibility of a near miss at a range where the building collapsing on top of everybody would be the biggest danger.
I would imagine at the time, the first strike would be in the hundreds, of not thousands of warheads. Coupled with the blast radius, missing doesn't seem relevant in that scenario.
Like the saying goes, "almost doesn't count except horseshoes, hand grenades and nuclear warheads."
During the era of "duck and cover," the Soviets had an extremely limited ability to strike the US. They had a mediocre bomber fleet which would probably have been torn to pieces by North American air defense. They had ICBMs from the late 50s, but not in significant numbers until well into the 60s. The popular idea of nuclear war starting with thousands of warheads coming in over the pole all at once wasn't really a possibility until the 70s or so.
