Authorities in the US state of Texas are investigating a massive explosion that rocked a chemical plant in Port Neches, southeast of Houston, in the early morning hours of Nov. 27.

The facility belonging to TPC Group was processing butadiene when the blast occurred. No environment monitoring data had been released at press time

Three people working at the plant that employs 175 people permanently and usually has as many as 50 employees of contractors on site were treated at hospitals.

 Reports conflicted as to the extent of the injuries, with some saying they were minor, while another said one worker had been transported by helicopter to a special burns unit in Houston.

In homes as much as 30 miles away, local news reports said windows were shattered and doors blown off. A mandatory evacuation order was issued for residents living within half a mile (800 meters) of the TPC site and following a second, smaller, blast extended to four miles,

The company processes petrochemicals used in production of synthetic rubber and polyamide, including – in addition to butadiene – butene-1, isobutylene derivatives and polyisobutylene.

Extensive damage to buildings in Port Neches (population around 13,000) was reported, and the US Coast Guard restricted navigation on the Sabine-Neches channel, which links refineries and terminals in the towns of Port Arthur and Beaumont, Texas.

Initially, there were no reports of any spill of chemicals into waterways. Due to the toxic smoke from the chemicals still burning well into the afternoon US time, personnel from the Texas Commission on Environmental Quality conducted handheld monitoring for various chemicals outside the evacuation zone.

The Texas section of the US Gulf chemicals belt has seen several accidents this year. Within two weeks last spring, a fire at the Deer Park tank farm owned by Intercontinental Terminals Company closed the Houston Ship Channel, and fire swept a plant owned by toll manufacturer KMCO in Crosby, claiming one life. In July, a fire at an ExxonMobil plant received national attention. The TPC site reportedly has also had safety issues.