LISBON (AP) - Authorities are trying to determine what snapped a cable supporting a wooden walking bridge suspended over the Sheyenne River, injuring five construction workers who were taking a break on the bridge in downtown Lisbon.

Police Chief Jeanette Persons said the bridge collapsed about 2 p.m. Wednesday, when the men were taking a break from a nearby paving job. She said no work was being done on the bridge at the time.

Authorities said two of the men were treated and released and three others were taken to Fargo hospitals. No names or conditions were immediately available.

Lisbon Public Works Superintendent Randy Seelig said the bridge was a wooden structure supported by two main cables. He estimated it was about 15 feet above the water and was believed to have been built by the National Guard in the 1970s. City officials said they were not sure Thursday who owned it.

"We just barricaded everything up so people can't get in there. We're just trying to keep people away as best we can," Seelig said.

Persons said firefighters and others from area businesses rushed to the scene when the bridge collapsed. When she got there, she said, one man was in the water and others were on the shoreline.

The police chief estimated the bridge was about 30 feet to 50 feet long.

"Right along the shoreline, it's about 2 feet deep. We were treating them (the workers) at the scene and getting them out of there as fast as we could," she said.

"This is a bridge that is used all the time - by students going to school, people going to doctors' appointments and going to the convenience stores, doing other business or going to church or just for a short walk," Persons said.

Two people had just crossed the bridge within 10 minutes of the collapse, the police chief said.

"It's been in there for so many years," Lisbon Mayor Ross Cole said. "It was used a lot by elderly people who lived on that side of town. It's an access to downtown for them, and it's a good cross way for kids. Thank God, nobody lost a life."

The bridge cables are being examined, officials said.

"It's kind of in the hands of the lawyers and stuff now," Cole said.