A series of explosions at the Chevron oil refinery in Richmond, California, has set off massive fires and a health scare for the surrounding communities. The blasts erupted early Monday evening, sparking blazing fires that sent large plumes of smoke into the sky. Residents of Richmond, North Richmond and San Pablo were ordered to stay in their homes with the windows and doors closed to avoid breathing in hazardous fumes. It was the latest in a series of fires at the more than 100-year-old Richmond plant. Around 200 people have reportedly sought medical treatment for respiratory issues. Chevron says the fire has been contained but not fully extinguished.