Operating excavators, tractors and other equipment on uneven terrain can be tricky. Doing so proved deadly for a young worker at a Ft. Myers, FL, construction site.

David Vasquez, 18, was grading soil on a grassy embankment at a housing project on the side of a manmade lake when the tractor he was operating slid or tumbled into the water. Preliminary investigation by the Lee County Sheriff’s Office suggests the victim may have had the tractor in the wrong gear, causing it to roll forward when he intended to put it into reverse gear.

Vasquez surfaced once and screamed for help, but he slipped under the surface soon afterward. A co-worker entered the water trying to help, but was not successful. Vasquez’s body was pulled from the water 30 minutes later and emergency workers tried to resuscitate him. They were unable to save the teenager.

spokeswoman for the South Trail Fire Department said Vasquez reportedly could not swim and no one at the site was a strong swimmer. She said supervisors who have crews working near water should ensure that one or more good swimmers capable of conducting water rescues are available in case a non-swimmer or weak swimmer falls into the water.