Getting beyond the gun obsessed with false equivalencies, this IS the time to consider how we can keep public places safe from this sort of attack. Other cities have taken steps to separate pedestrians from auto traffic. It may be that places with heavy foot/bike traffic need to be protected by planters/bollards/ benches or other barriers. Places like the 16th street mall come to mind and campuses as well.

We can never be 100% safe, but steps can be taken to minimize the risks to the public.