(PORT NECHES, Texas) — At least three people were injured when a powerful explosion erupted at a petrochemical refinery in Texas early Wednesday morning, officials said.Video and images taken by people in the area and posted online show a massive fireball illuminating the dark sky over the TPC Group plant in Port Neches, Texas, about 15 miles southwest of Beaumont.The early morning explosion involved a processing unit, and three personnel on site sustained injuries and are being treated. All staff at the plant have since been evacuated and accounted for, according to a press release from TPC Group.”The event is ongoing, but will be brought under control as quickly and safely as possible,” the company said in a statement Wednesday. “Right now our focus is on protecting the safety of responders and the public, and minimizing any impact to the environment.”Jefferson County Judge Jeff Branick told ABC News that the plant was still on fire hours after the blast.A mandatory evacuation was in effect for residents living within a half-mile radius of refinery. A fire department spokesperson in the neighboring city of Nederland told ABC News that evacuation orders could expand to a wider area.A highway near the plant was shut down, and there were reports of damaged homes in the area, according to a spokesperson for the Port Neches Police Department, who expressed concern about chemicals in the air and possible secondary explosions.Copyright © 2019, ABC Radio. All rights reserved.