BRYAN, Texas (AP) — A third worker has died of injuries from a Central Texas oil well blowout, the company said Monday.

Chesapeake Energy spokesman Gordon Pennoyer said in a statement the company is “deeply saddened” by the worker’s death. Pennoyer did not say when the worker died.

The worker was injured in Wednesday’s blowout at a Chesapeake Energy well site near Deanville, about 75 miles (120 kilometers) east of Austin.

One worker died at the scene while another three were airlifted on Wednesday to hospitals in Austin and Houston. A second worker died on Thursday.

The condition of the other injured worker was not immediately known.

No identities have been released, but Pennoyer said the four were employed by contractors who were replacing drilling hardware on the well.

A blowout is an eruption of oil or gas from the wellhead that can erupt in flames if there is an ignition source, such as a spark.

The cause of the incident remains under investigation, Pennoyer said.

Chesapeake Energy is based in Oklahoma City.

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