Although chromosomal deletions and inversions are important in cancer, conventional methods for detecting DNA rearrangements require laborious indirect assays. Here we develop fluorescent reporters to rapidly quantify CRISPR/Cas9-mediated deletions and inversions. We find that inversion depends on the non-homologous end-joining enzyme LIG4. We also engineer deletions and inversions for a 50 kb Pten genomic region in mouse liver. We discover diverse yet sequence-specific indels at the rearrangement fusion sites. Moreover, we detect Cas9 cleavage at the fourth nucleotide on the non-complementary strand, leading to staggered instead of blunt DNA breaks. These reporters allow mechanisms of chromosomal rearrangements to be investigated.