Officials: Spark ignited propylene leak causing explosion at Watson Grinding

HOUSTON – An electrical spark ignited a propylene leak at a Spring Branch business last week and caused an explosion that damaged more than 400 surrounding buildings, officials said Friday.

Investigators with the Bureau of Alcohol, Tobacco, Firearms and Explosives said propylene began leaking from one of the tanks at Watson Grinding and Manufacturing sometime between 1 a.m. last Thursday and 1 a.m. last Friday. The blast was reported about 4:20 a.m. last Friday.

ATF investigators said they believe an electrical spark that is a normal part of any electrical system ignited the leaking gas.

The blast killed two employees of the business.

There is no indication that arson, sabotage or vandalism was involved in the blast, ATF investigators said.

Houston fire Chief Sam Peña said that the ATF’s finding is preliminary. He said a final determination of the cause could take as long as two months.

Houston police Chief Art Acevedo said patrols of the affected neighborhoods will continue and there have been no reports of looting in the area.

This is a developing story.