Ten workers were killed and five are injured in the collapse of a partially-constructed bridge across a valley outside of Colombia's capital city Bogota. 

Most of the workers on the project were not on the bridge at the time, fortuitously being summoned to a safety lecture.  But others were working on the bridge's drainage system.

"Everyone started shouting that the bridge was falling, I didn't have time to do anything and then I felt a blow to my head," said Luis Alvarado to the newspaper El Tiempo.

Chirajara, Colombia

Chirajara, Colombia

One of the bridge's two towers collapsed, and debris - and bodies - crashed down into the valley below.  The scene quickly turned to chaos.

"There was a lot of smoke, and desperation in all directions.  As we were evacuating we turned around to look that way, the beam was no longer there," said worker Maicol Lopez, who was on the opposite side of the span.  "We came to try and help our friends, but unfortunately, well, they died."

Nine died instantly, the tenth died at hospital.

The 446-meter-long bridge was expected to be opened in March to be part of a brand new major highway system connecting the capital Bogota with the city of Villavicencio as part of President Juan Manuel Santos' "4G" infrastructure project.