Teachers' sensemaking of student behavior determines whether students get in trouble and are formally disciplined. Status categories, such as race, can influence perceptions of student culpability, but the degree to which teachers' initial identification of student misbehavior exacerbates racial disproportionality in discipline receipt is unknown. This study provides the first systematic documentation of teachers' use of office discipline referrals (ODRs) in a large, diverse urban school district in California that specifies the identity of both the referred and referring individuals in all ODRs. We identify teachers exhibiting extensive referring behavior, or the top 5% referrers, based on the number of ODRs they make in a given year and evaluate their contributions to disciplinary disparities. We find that "top referrers" effectively double the racial gaps in ODRs for both Black-White and Hispanic-White comparisons. These gaps are mainly driven by higher numbers of ODRs issued for Black and Hispanic students due to interpersonal offences and defiance and also partially convert to racial gaps in suspensions. Both the level and racial compositions of the school sites where top referrers serve and their personal traits seem to explain some of their frequent referring behavior. Targeting supports and interventions to top referrers might afford an important opportunity to reduce racial disciplinary gaps.