The U.S. government has drastically understated the number of people killed in high-speed police car chases, potentially by thousands of fatalities over several decades, a USA TODAY investigation shows.

The National Highway Traffic Safety Administration overlooked at least 101 motor-vehicle deaths in 2013 that were related to a police chase, according to a USA TODAY review of police reports and internal documents, court records, police-car videos and news accounts based on police statements. NHTSA’s count of 322 chase-related deaths in 2013 — the most recent year for which its records are publicly available — understates the total by at least 31%, the investigation shows.

NHTSA’s undercount suggests that the actual number of people killed in police chases since 1979 could be more than 15,000 — far more than the 11,506 chase-related deaths found in the agency’s public records — and that chases result in a death much more frequently than studies have stated.