The present invention provides compositions, apparatuses and methods for detecting one or more nucleic acid targets present in a sample. Methods of the invention include utilizing two or more oligonucleotide probes that reversibly bind a target nucleic acid in close proximity to each other and possess complementary reactive ligation moieties. When such probes have bound to the target in the proper orientation, they are able to undergo a spontaneous chemical ligation reaction that yields a ligated oligonucleotide product. In accordance with the invention, the presence of the target(s) of interest can be determined by measuring the presence or amount of ligated oligonucleotide product.