There have been no reports of injuries but damage to buildings in the vicinity is widespread as the explosion.
An explosion at a chemical plant in Texas early Wednesday sent a large fireball into the sky, media reports said, triggering a mandatory evacuation.
"Please be aware that there is a mandatory evacuation for everyone within a 1/2 mile of the TPC plant in Port Neches," local fire officials said in a post on the Nederland Volunteer Fire Department's Facebook page.
Dramatic videos and photos shared on social media showed a massive explosion, with one resident describing waking up to a huge boom and "glass all over us".
Ryan Mathewson, who lives roughly two minutes from the plant with his family, told AFP: "We woke up to glass all over us and parts of the ceiling caved in, (and) doors blown in."
The 25-year-old said they were "shook up and scared" following the blast.
County Judge Jeff Branick told local news site KFDM News that there were no injuries reported.
The site of the explosion is believed to be a petrochemical plant roughly 85 miles (135 kilometers) from Houston.