Lyondell Basell Industries extinguished a fire on a hydrotreater on Thursday morning at its 263,776-barrel-per-day (bpd) Houston refinery, said sources familiar with plant operations.

The extent of damage to the 50,000-bpd 635 diesel hydrotreater was unknown early on Thursday, the sources said.

The fire broke out after an overhead pipe burst, the sources said.

There was no immediate information about any injuries from the fire, the sources said

In a message posted on a community alert site at 5:55 a.m. CDT (1055 GMT), Lyondell said it was burning hydrogen and hydrogen sulfide material in the refinery's safety flares "due to a process upset/fire."

The hydrotreater uses hydrogen to remove sulfur from diesel to comply with U.S. environmental rules.

(Reporting by Erwin Seba; editing by David Evans and Jonathan Oatis) ((erwin.seba@thomsonreuters.com; +1 713 210 8508; Reuters Messaging: erwin.seba.thomsonreuters.com@reuters.net))