An explosion struck the Valero oil refinery in the city of Port Arthur, Texas, on Monday, prompting authorities to issue shelter-in-place orders for residents in nearby areas.

Officials from Port Arthur’s emergency management department stated that the decision was taken to “ensure the safety of all residents in the area surrounding the refinery” following the blast, noting that the warning covers a wide range of nearby areas.

For its part, Valero announced that a fire had broken out in one of the refinery’s units, confirming that all employees are safe and stressing that “worker safety remains a top priority.”

According to local media reports, large flames and a thick column of black smoke were seen rising from the refinery. Residents in surrounding neighborhoods also reported hearing a powerful explosion that caused windows to shake.

The refinery employs approximately 800 workers and specializes in processing heavy sour crude oil and other feedstocks, converting them into gasoline, diesel, and jet fuel, according to Valero’s official website.

The incident comes at a time when energy markets are experiencing heightened tensions due to geopolitical escalations in the region, stemming from the U.S.-Israeli aggression against Iran. This situation makes any disruption to American oil facilities a potential factor influencing supplies and prices.