HOUSTON, Texas (KTRK) -- As homeowners cleaned up and investigators sifted through debris for a cause of Friday morning's blast at Watson Grinding & Manufacturing, company leaders kept quiet.
RELATED: Massive blast damage field treated as crime scene
A Friday morning phone call with the company's CEO confirmed his plant was the site of a propylene explosion. Attempts to get other answers were unsuccessful.
How will the company help impacted homeowners? What was the company doing at 4:20 Friday morning? What caused the blast? No answers to any of that.
Houston's fire chief confirmed what images from SkyEye showed - there was no tank explosion. HFD Chief Sam Pena told 13 Investigates the early suspicion leads them to suspect a propylene leak, but the investigation would confirm it.
BEFORE AND AFTER: Click here for an interactive slider to compare the area before the blast and its aftermath
Propylene is an industrial chemical. The Emergency Response Guidebook says propylene vapors can initially be heavier than air and spread along the ground. They are easily ignited by any spark.
Propylene can be used in cutting applications and powder-coating - Watson does both, but it's unclear if the company was in operation at 4:20 a.m.
Houston Mayor Sylvester Turner said an employee may have been working out at the facility early this morning. The company's website shows pictures of an impressive fitness facility.
WATCH: Moment of explosion caught on video at Watson Grinding in NW Houston
As for the company's history, the Occupational Safety and Health Administration fined the company $8,000 in a negotiation settlement in 2013 for serious violations. The notices for the serious violations relate to machine operations.
The Texas Commission on Environmental Quality does not list any violations in their compliance history for Watson Grinding and Manufacturing.
For the latest investigations, follow Ted on Facebook and Twitter.
Have a tip for Ted Oberg? A problem to solve? Get in touch with us on our tip page, or send a tip below. (On mobile? You can open our form by tapping here.)
Houston explosion: Company history OK, but few answers Friday
TED OBERG INVESTIGATES