More photos » by Matt Slocum - AP

Dallas Cowboys chief operating officer Stephen Jones, left, talks on a phone after the canopy that covered the Cowboys indoor football facility collapsed,

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The cause of yesterday's practice facility collapse is a bit of a mystery as local authorities found no other damage outside the immediate area. The storm that hit the dome was nearly as powerful as a tornado.

The storm was producing winds measured at 64 mph just before it struck the Cowboys facility, said National Weather Service meteorologist Joe Harris in Fort Worth. A weak tornado is in the range of 65-110 mph, according to NWS guidelines. Power was knocked out for less than an hour.

The DMN is currently investigating the manufacturers of this particular steel-framed building.

The manufacturers, Summit Structures and Cover-All Building Systems, tout their work in building other sports facilities, including ones for the New England Patriots and Texas A&M. But I can't find any mention on the company Web sites of the Cowboys facility. Why?

Another issue we're looking at: A Summit-built warehouse in Pennsylvania partially collapsed during a 2003 snowstorm, less than two months after opening. A 2007 court order blamed Summit for design flaws.

ESPN's Matt Mosely on the facility:

Before Bill Parcells was hired as coach in 2003, the Cowboys rarely practiced indoors, unless weather was bad enough for them to ride buses to a high school team's bubble. Parcells suggested that owner Jones build one, and it was finished in time for Parcells' first season at a cost of more than $4 million.

The no-frills building was pretty much a 100-yard football field with a few more yards of clearance all the way around. The roof was 80 feet high, the equivalent of an eight-story building.

On yesterday's weather:

National Weather Service meteorologist Gary Woodall said a "microburst" may have pushed the wind beyond 70 mph at the top of the structure. A microburst also was to blame for a 1985 Delta Airlines crash at nearby DFW airport that killed 137 people.

Mosely's injury update:

Here's what I know on the injuries: Special teams coach Joe DeCamillis was set to undergo surgery for two broken verterbrae, but the prognosis is good. Cowboys assistant scout Rich Behm underwent surgery on his spinal cord late last night at Parkland Memorial Hospital and I'm not sure about his condition.

I'm told that head coach Wade Phillips and owner Jerry Jones were both with Behm's family at the hospital Saturday night. We'll keep you updated throughout the afternoon.

Brad Townsend spoke with LB Bobby Carpenter and got his reaction to the bad news.

"To think that something like that could happen," Carpenter said, shaking his head. "We've been in there when it's been windy, a little bit of light-shaking, but nothing quite that extreme."

Today, Carpenter was on his way to lunch with DBs Deangelo Smith and Mike Mickens.

Smith, Mickens and other draft picks and free agents who took part in the rookie minicamp declined to comment Sunday, other than to say they were OK. Several players said the Cowboys organization had asked them not to speak to media members about Saturday's calamity that sent 12 people to hospitals.

Jerry Jones visited the site this morning.