About 300 boy scouts were treated for heat exhaustion Wednesday, while waiting for President Bush to arrive at a memorial service for four Scout leaders, killed as they pitched a tent beneath a powerline.

The president's visit to the Scout Jamboree at Fort A.P. Hill is postponed because of severe thunderstorms and strong winds. Bush is scheduled to visit the gathering Thursday.

Before the president's visit was cancelled, however, a number scouts fell ill from temperatures rising well into the upper 90's, which, when coupled, with the high humidity, proved to be overwhelmingly scorching.

Half are treated and released from base hospital, about three miles from the event area. Dozens more are sent to other hospitals, where they remain in stable condition as of Wednesday night.

Jamboree officials called on surrounding areas for emergency aid, while ambulances transport Scouts to the hospital, during a storm that contained high winds and lightning.

It was the latest tragedy to malign the event since Monday, when the four Scout leaders were electrocuted while pitching a dining tent, ignoring Scout teachings, and placing the tent under a power line.

Jamboree spokesman Gregg Shields said the tragedy was unusual, as Boy Scouts are taught not to put their tents under trees or power lines.