The death toll from Wednesday's explosion at a Texas oil refinery has risen to 15 people.

Petroleum company BP increased the death toll Thursday to include a worker previously thought to have left the refinery sometime Wednesday.

More than 100 others were injured in the blast, which rained ash and debris on the surrounding town of Texas City.

BP has not identified the cause of the blast but it says terrorism is not a primary focus of its investigation.

Federal investigators will conduct their own review of the incident.

The refinery processes about 460,000 barrels of crude oil per day, accounting for three percent of the U.S. fuel supply.

The blast was the second fatal incident at the plant in the past year.

Some information for this report provided by AP and AFP.