HOUSTON (AP) — U.S. officials cited the owners of a Southeast Texas chemical plant where November blasts and fires injured three workers and caused widespread damage to the surrounding community.

The Nov. 27 blasts at the TPC Group plant in Port Neches, about 80 miles (129 kilometers) east of Houston, prompted officials to order the surrounding communities to be evacuated of about 50,000 residents.

The Occupational Safety and Health Administration said in a statement Tuesday that it cited TPC for three willful violations by not developing and implementing procedures for emergency shutdown and not inspecting and testing process vessel and piping components. TPC faces $514,692 in civil OSHA fines.

TPC has 15 business days from receipt of the citation and penalties to comply, request an informal conference with OSHA’s area director or contest the findings before the independent Occupational Safety and Health Review Commission. A message with a TPC spokesman Wednesday was not immediately returned.

An investigation found that vapor formed at the base of a butadiene finishing tower and ignited, causing the explosions and fires.