One of the men later died in the emergency room of Harborview Medical Center. The other remains in critical condition.
Rescue crews were called to the lake about about 9:30 p.m. after getting reports of two swimmers struggling and going under water. One of the witnesses went in after the men, but couldn't find them. Other witnesses stayed on shore and called 911, according to Kyle Moore with the Seattle Fire Department.
"Those witnesses stayed on scene, which was very helpful. They pinpointed exactly where they saw them go down, and we're running a grid search from that location out," Moore said.
Dive crews from the Seattle Police and Fire Departments arrived on scene moments later and began looking for the men roughly 50 yards off the shore.
"Whenever you have someone under water, we want to get as many trained crews out here as quickly as possible because every second counts," Moore said.
Roughly 35 minutes after the first emergency call came in, divers found a 26-year-old man underwater and pulled him to the shore. Moore said that man was unconscious and unresponsive. Medics performed CPR on the man while transporting him to Harborview Medical Center.
Ten minutes after they found the first swimmer, divers discovered the second unconscious man. He, too, was taken to Harborview.
One of the men later died. The other remains in critical condition.