City and county leaders Wednesday unveiled warning signs at several "hot spots" in the South Bay where high levels of hydrogen sulfide gas from the Tijuana River pollution crisis have been recorded.

Officials revealed warning signs in South Bay hotspots amid ongoing Tijuana River pollution, with efforts to inform and protect affected communities.

Train derailments involving spills of 1,000 gallons or more of hazardous materials happen a few times a year, often resulting in evacuations or fires. The ...