Explosions at a U.S. Steel plant that shook the ground near Pittsburgh left one dead and sent at least 10 to hospitals Monday, with emergency workers still searching the badly charred rubble hours later for a missing worker, officials said. One worker was pulled from the wreckage hours after the explosions sent black smoke spiraling into the midday sky in the Mon Valley, a region of the state synonymous with steel for more than a century. Allegheny County Emergency Services said a fire at the plant started around 10:51 a.m. A search and rescue effort was still active on Monday afternoon and officials said they had not isolated the cause of the blasts. Read more at: https://www.9news.com/article/news/nation-world/explosion-us-steel-coking-plant-in-pennsylvania/507-efb85944-cc35-474c-8fed-0f11699ed9ea More local videos here: https://youtube.com/@9news Subscribe to NEXT: https://youtube.com/@Nexton9NEWS Stay connected: 9NEWS Website: https://www.9news.com/ Facebook: https://www.facebook.com/ilike9news X: https://twitter.com/9NEWS Instagram: https://www.instagram.com/9newsdenver/ Download the 9NEWS App: https://www.9news.com/appredirect/ Sign up for the 9NEWSLETTER: https://www.9news.com/email 9NEWS (KUSA) is located in Denver, Colorado.