That's very easy for me to write while I'm behind the safety of a computer half a country away.
None of us can predict how we would react in such a situation.
However it it possible that the sniper (under cover of nearby woods) waits for a (very common) white minivan type of vehicle that is ready to leave ....then he shoots his victim.
When the minivan speeds off; bystanders natually assume it was involved.
Other local reports this morning indicated that the white van was bumping cars trying to get away...