Hamilton County, TN Office of Emergency Management & Homeland Security via Twitter

(CHATTANOOGA, Tenn.) —

Eleven people were injured, two critically, when an elevated deck of a Tennessee waterfront restaurant collapsed during a birthday party group photo, authorities said.

The joyous festivities turned to a moment of terror on Saturday afternoon in suburban Chattanooga when an outdoor wooden deck at Zois Harbor Lights Restaurant suddenly gave way under the weight of more than 40 people posing for a birthday group photo, according to the Hamilton County Emergency Management Agency.

The episode unfolded around 4 p.m. at the restaurant in Soddy-Daisy overlooking Chickamauga Lake, officials said.

Photos posted online by the Office of Emergency Management showed the large wooden deck caved in and splintered, lying in shambles amid broken railing, toppled support beams and twisted aluminum siding.

Amy Maxwell, spokesperson for the county Emergency Management Agency, told ABC News on Sunday that when the collapse occurred some people were trapped underneath the deck while others walked away with minor injuries.

One of those injured, Sondra Teligades, told ABC affiliate station WTVC-TV in Chattanooga that she heard cracking noises and described panic of free-falling for roughly two stories to the ground at the edge of the lake. Teligades said she was taken to a hospital and treated for a concussion and rib contusions.

Firefighters from Dallas Bay and Soddy-Daisy responded to the scene and began performing first aid on those injured.

Officials said 11 people were taken by ambulance to nearby hospitals. Two patients were critically injured, according to Maxwell.

Maxwell said it was not immediately clear why the deck collapsed.

Maxwell said the Hamilton County Building Codes Department is investigating the incident.

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