BACKGROUND: Accurate mortality estimates help quantify and memorialise the impact of war. We used multiple data sources to estimate deaths due to traumatic injury in the Gaza Strip between Oct 7, 2023, and June 30, 2024. METHODS: We used a three-list capture-recapture analysis using data from Palestinian Ministry of Health (MoH) hospital lists, an MoH online survey, and social media obituaries. After imputing missing values, we fitted alternative generalised linear models to the three lists' overlap structure, with each model representing different possible dependencies among lists and including covariates predictive of the probability of being listed; we averaged the models to estimate the true number of deaths in the analysis period (Oct 7, 2023, to June 30, 2024). Resulting annualised age-specific and sex-specific mortality rates were compared with mortality in 2022. FINDINGS: We estimated 64 260 deaths (95% CI 55 298-78 525) due to traumatic injury during the study period, suggesting the Palestinian MoH under-reported mortality by 41%. The annualised crude death rate was 39·3 per 1000 people (95% CI 35·7-49·4), representing a rate ratio of 14·0 (95% CI 12·8-17·6) compared with all-cause mortality in 2022, even when ignoring non-injury excess mortality. Women, children (aged <18 years), and older people (aged ≥65 years) accounted for 16 699 (59·1%) of the 28 257 deaths for which age and sex data were available. INTERPRETATION: Our findings show an exceptionally high mortality rate in the Gaza Strip during the period studied. These results underscore the urgent need for interventions to prevent further loss of life and illuminate important patterns in the conduct of the war. FUNDING: None.