OSHA has cited Horizon Biofuels Inc. for willful and serious safety violations after a deadly explosion at the company’s Fremont facility in July 2025. An investigation was initiated on July 29, 2025, following the explosion that caused fatal injuries to a worker. OSHA cited Horizon Biofuels for violations including combustible dust buildup, failure to ensure equipment within the facility was protected from creating an ignition source and lack of fall protection for employees working at heights greater than four feet. The citations carry $147,542 in proposed penalties.