BAYTOWN, Texas (AP) – Crews have extinguished a large fire at a Houston-area refinery that left four people injured.

The fire started at about 1 a.m. Thursday at ExxonMobil’s refinery in Baytown, which is about 25 miles east of Houston.

The company says four people were hurt but everyone else on site has been accounted for. The cause of the fire is not yet known.

ExxonMobil says air quality monitoring has not revealed any issues. No evacuations or shelter-in-place orders have been issued.

The refinery employs about 7,000 people and has the capacity to process up to 584,000 barrels of crude oil each day.