All but two of the 119 Navy recruits who were sent to 10 San Diego hospitals late Saturday night with complaints of breathing difficulties were released early Sunday after being treated with oxygen, Navy and hospital spokesmen said.
The recruits, nearing the end of their second week of training at the Navy Training Center on Rosecrans Street, were in three barracks after a day of sports and barbecues when several of the 18- and 19-year-olds said they were wheezing, despite the open windows, said Navy Lt. Kenneth Luchka.
The Navy evacuated 600 men from the barracks starting at 9:30 p.m. and alerted county medical emergency authorities, who routed more than 50 ambulances to the scene by about 11 p.m. County Hazardous Materials officials found no evidence of toxic fumes, food poisoning or any other cause, Luchka said.
"We still don't know what caused it. We are thinking on the contention that the unit had physical training together and could have spread a virus. Particles in the air from fires, a smog alert, and the heat could have combined to make some sick. There is a possibility the others might have thought they were sick after that," he said.
"There were no toxic chemicals in their blood, so there is a possibility of mass hysteria."
The Navy is conducting a medical investigation, he said.
The two recruits still at Sharp Cabrillo Hospital were listed in stable condition Sunday afternoon.