A pedestrian bridge under construction collapsed Friday morning near the entrance of the Atlanta Botanical Garden, killing one worker and injuring 18 others.

Builders were working on the "canopy walk" that arches over a ravine to give visitors an elevated view of the new gardens when the structure gave way around 9 a.m. Joggers, dog walkers and others were visiting popular adjacent Piedmont Park, but it appeared only workers were in the 30-acre garden.

Electrical worker Juan Padilla and his partner were taking a break from doing work under the bridge at the time of the collapse.

"It sounded like an explosion," he said.

Padilla said he knew many of the victims, and fought back tears. "It was so tough," he said. "I feel very lucky. Me and my partner, we could have been under the bridge."

All of those injured were workers, many with cuts, bruises and fractures. A few were carried out on backboards to waiting ambulances at the park north of downtown Atlanta, said Atlanta Fire Capt. Gregory Shinkle.

Between five and seven of the injured taken to Grady Memorial Hospital were in critical condition when they arrived, said hospital spokesman Denise Simpson. Authorities have not released the name of the person killed.

An Occupational Safety and Health Administration officer was on the scene to see if safety standards were followed, said OSHA spokesman Mike Wald.