KINGSPORT, Tenn. — A company says it doesn’t expect coal gas explosions at its Tennessee chemical plant to threaten human health or cause long-term environmental impacts.

Eastman Chemical said two explosions and a fire Wednesday morning at its Kingsport manufacturing facility resulted from what it called “a process upset.”

Eastman said there were no injuries beyond minor first aid.

Neighbors were warned to shelter in place amid a black smoke plume. People living within a half-mile had to stay put for four and a half hours.

Eastman chief legal officer David Golden says carbon monoxide and hydrogen were within the emissions, but the release was at a concentration and direction that doesn’t threaten human health or the environment.

Golden says Eastman is still investigating the cause. Unaffected areas of the plant are restarting.