(CNN) -- An air-supported canopy over the Dallas Cowboys' practice field collapsed during a heavy thunderstorm Saturday afternoon, leaving one person critically injured and six others hurt, firefighters said.

As many as 80 people may have been inside the facility when it was blown down shortly before 3:30 p.m. (4:30 p.m. ET), said Mike Adams, a dispatcher for the Irving, Texas, fire department. Rescuers were continuing to comb through the wreckage beneath the fallen canopy, but, "Everyone as far as we know is accounted for," Adams said.

Video from CNN affiliate WFAA showed the canopy caving in during a heavy storm, sending players, coaches and a handful of reporters and photographers scrambling to escape.

WFAA-TV photojournalist Arnold Payne, who was on the sidelines of the indoor practice field when the collapse occurred, said the wind "just started shaking the sides of this big huge plastic practice tent."

"The lights started swinging from the ceiling, and just like that ? the thing just started collapsing," Payne said. "They could hear people under there screaming; I could see two or three people injured.".

Cowboys' owner Jerry Jones told NBC that about 27 rookies from the NFL team and members of the team's coaching staff were inside the suburban Dallas facility at the time.

"They did not get good warning there, and the structure did collapse," Jones said, speaking from the Kentucky Derby in Louisville. "We're assessing who's injured at this particular time."

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