Four were killed and about 40 were injured when a tornado swept through a western Iowa Boy Scout camp just after 6:30 Wednesday night. It’s unclear what sort of shelter was available for the 93 Boy Scouts and 25 adults who were at The Little Sioux Scout Reservation campground.

Governor Chet Culver spoke with officials on the scene, then briefed reporters by phone shortly after 10 o’clock  "This is a very, very horrific scene and a very tragic event," Culver said.

Iowa Public Safety Commissioner Gene Meyer said search and rescue teams are still combing through the camp and checking the patient rosters at local hospitals, looking for three campers. "If any parents happened to pick up their children or evacuated their own children, we need to know that. We’re still trying to account for everyone and if any parent did that, we need for them to call the Harrison County, Iowa Sheriff’s Department," Meyer said.

A week-long leadership training session was underway for teenage campers from Iowa and Nebraska. The camp is situated in the Loess Hills, sort of midway between Sioux City and Omaha.  "We are profoundly saddened and hold the families of those killed or injured up in prayer and our heart goes out to all of the families and the children affected by this horrific tragedy," Culver said to open the call.

Officials say rescue efforts are complicated because the camp is in a heavily-wooded area about three-quarters-of-a-mile from a passable road and weather conditions were brutal. Torrential rain was falling and lightning was striking the areas in the hours after the tornado struck. "All of the professionals, the emergency response teams, are on the ground working feverishly to try to determine precise numbers and to try to get people the medical attention that they need," Culver told reporters.

Those who were injured in the tornado were taken to at least five different hospitals in Council Bluffs, Omaha, Sioux City, Missouri Valley and Onawa. The names and ages of those who were killed have not being released. Lights were trucked into the area so Iowa National Guard teams, alongside emergency responders and state troopers, could work in the dark, looking for the missing campers. "We have three that we’re calling missing, but they could be at a local hospital. They could have been picked up by someone," Public Safety Commissioner Meyer said at about 10:15 p.m., "but our search does continue."

Dave Miller, director of Iowa Homeland Security, said the National Weather Service issued two tornado warnings for the area but it is unclear whether sirens were sounded on the campground.

Click on the audio link below to listen to the news briefing.

AUDIO: News briefing on tornado (mp3 runs 7 min)

Radio Iowa