HOUSTON—A chemical plant worker was killed and six others injured during an early morning explosion and ammonia leak Wednesday at the Goodyear Houston plant.

The body of the worker, whose name was not released, was found under debris about seven hours after the 7:30 a.m. blast in a heat exchange unit at the plant, said Goodyear spokesman Scott Baughman.

One of the injured workers was in intensive care at Ben Taub Hospital. One worker was being held for observation at an area hospital, and three others were treated and released, plant officials said.

The explosion also caused a small release of ammonia, which is used as a refrigerant to cool processed liquids.

The six injured were treated on-site by the plant’s medical team before being transferred to local hospitals. Baughman said the damage and small ammonia spill were contained in a small area of the plant, which makes synthetic rubber for the production of tires.

The plant was evacuated for several hours after the explosion. About 200 people were in the plant at the time.

There was no danger to the public, plant officials said.

The plant was given an “all-clear” around 11 a.m., when employees were allowed back in to the facility. The area near the explosion remained closed, Baughman said.

The blast happened in one of the plant’s three heat exchanging units, which are about 2 feet wide and 15 feet long. The units use ammonia, Baughman said.

Plant officials were investigating the cause of the explosion and trying to determine how much ammonia was spilled.