What does the indefinite pronoun einige point to, in this sentence?
This is a much better question than the downvotes are suggesting :).
Grammatically, what you can observe here is the so-called "Distanzstellung" of an indefinitum (here: "einige"). With that in mind, just note that the sentence is basically a "rattled" version of
An dieser Stelle hat es schon einige Unfälle gegeben.
The reason is generally contextual, but preferences also vary regionally. (You provide no context.)
Such a "flexibility" can be observed with other indefinita as well, e.g. kein or manche. It's not confined to German, but a phenomenon observed across a wide variety of languages (the term of art is "quantifier floating", should you wish to dig deeper).
It means "a few" and is talking about a few accidents. Unfälle are accidents.