Complex sentence: In July, dozens of Koreans who tried to escape the construction site were gunned down or otherwise killed by the plant foremen, were dipped in cement, and were cast into the Shinano River.
Split into simpler sentences: In July, dozens of Koreans who tried to escape the construction site were gunned down or otherwise killed by the plant foremen. The workers' bodies were then dipped in cement, and cast into the Shinano River.