PORT NECHES, Texas (AP) - The Latest on an explosion at a chemical plant in Texas (all times local):

8:30 a.m.

Environmental officials are monitoring the air quality after an explosion at a Texas plant sent a huge plume of smoke into the sky.

Jefferson County Emergency Management coordinator Mike White tells the Beaumont Enterprise that no elevated chemical levels have been detected so far after the 1 a.m. Wednesday explosion at a TPC Group plant in Port Neches, about 80 miles east of Houston.

Two TPC employees and a contractor were injured in the blast, which also blew out windows and knocked down doors at nearby homes. White says five residents are being treated for minor injuries, mostly related to shattered glass.

TPC said later Wednesday morning that it had no details on the cause of the explosion or the extent of damage to the plant.

2:30 a.m.

A plant that produces chemical and petroleum-based products in East Texas has exploded, blowing out windows on homes several miles away.

KFDM-TV reports that County Judge Jeff Branick says the explosion originated at a plant in Port Neches, near the Louisiana border.

TPC Group says on its website that it provides a diverse range of quality products to chemical and petroleum-based companies worldwide. The site says the company employs more than 175 full-time employees and 50 contractors.

The Nederland Volunteer Fire Department said on its Facebook page that there is a mandatory evacuation for everyone within a half mile of the TPC plant. It said the evacuation could expand to a greater area.

No injuries have been reported.

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