The present study aimed to identify the contributions of sociodemographic factors, psychological hardiness, and pandemic‐related stressors to the development of peritraumatic distress and posttraumatic stress symptoms (PTSS) during the peak of the COVID‐19 pandemic. We also examined the mediating contribution of peritraumatic distress with respect to the associations between PTSS and (a) individual characteristics and (b) pandemic‐related stressors. A total of 1,238 participants (82.1% women, 17.9% men) aged 18–75 years were included in the study. Participants completed the Dispositional Resilience Scale, Peritraumatic Distress Inventory, and Posttraumatic Stress Disorder (PTSD) Checklist. The results showed that 11.5% of participants scored above the clinical cutoff for peritraumatic distress, and 12.8% of participants scored above the clinical cutoff for PTSS. Regression models showed that higher levels of peritraumatic distress were statistically predicted by female gender, β = ‐.12, p < .001; exposure to more than one stressor, β = .21, p < .001; lower levels of commitment to people and activities, β = –.12, p = .002; and resistance to challenges, β = –.17, p < .001. Additionally, male gender, β = .05, p = .007; younger age, β = –.05, p = .005; lower levels of commitment to people and activities, β = –.11, p < .001; lower ratings of hardiness with regard to challenge, β = –.04, p = .043; and more severe peritraumatic distress, β = .75, p < .001, predicted more severe PTSS during the pandemic. Peritraumatic distress mediated the associations between PTSS and both the number of experienced stressors and psychological hardiness.