A witness said it was sleeting when he heard the helicopter flying low over a field near the small town of Compton south of Rockford shortly after 8 p.m. Monday.



"It was really crappy out," said Micheal Bernardin, a Viola Township highway commissioner who lives near U.S. Route 30 and Illinois Route 251. "I'd call it sleet, I guess was coming in, and I think they ran into that stuff and I've got an idea that weather was an issue."



The National Weather Service reported light snow in the area at the time, with winds from the west at 7 mph and visibility around 7 miles. The temperature was 28.



Bernardin said it appeared the pilot steered clear of surrounding farm buildings before the helicopter dove into the ground.



"It sounded like it was going to hit the house,'' Bernardin said. "All of a sudden I saw this red light come out of the sky and nosedive right into the ground out here. I thought it was going to hit the house, but evidently the guy steered her clear of everything."



Bernardin said he and his wife jumped into their pickup truck and spotted the wreckage in the headlights. "It was unbelievable, unbelievable," he said. "Oh my God, three people died."



Lee County Sheriff John Varga said it did not appear the helicopter hit any power lines or other structures. "The phone calls and witnesses we got last night said something didn't sound right, it was flying low," he said.



The helicopter was registered to Rockford Memorial Hospital and was en route to pick up a patient at Mendota Community Hospital, officials said. The patient was later taken by ambulance to Rockford.



The Rockford hospital identified the victims as:



-- Jim Dillow, 40, who joined Rockford Memorial Hospital in 1996 and had more than 10 years of experience as a flight nurse.



-- Karen Hollis, 48, who joined Rockford Memorial Hospital in 1986 and also had more than 10 years experience as a flight nurse.



-- Andy Olesen, 65, the pilot who was employed by Air Methods of Denver used by hospital. Relatives said he flew helicopters in the military and served in Vietnam. He was planning to retire next week and only had four more shifts left.



"Andy was an experienced pilot when he began flying for Air Methods in 1994 and had been a pilot for Regional Emergency Acute Care Transport for about five years," said Dr. Dennis Uehara, chairman of emergency medicine at Rockford Memorial Hospital.



The hospital was contacted about 7:30 p.m. Monday by Mendota Community Hospital to pick up a patient, Uehara said, declining to disclose the nature of the patient's illness.



The helicopter left from a hangar on the Rockford hospital campus a few minutes later, Uehara said. The dispatch center received word from Olesen that he and the crew had "encountered weather" and were turning back.



That was the last they were heard from, Uehara said. About 10 minutes later, the dispatcher tried unsuccessfully to contact the helicopter.



Varga said his office received a call from the Rockford hospital at about 8:15 p.m. saying they had lost contact with the helicopter.



The European-made helicopter was about 25 years old, according to Ron Meadors, director of the Regional Emergency Acute Care Transport (REACT) at the hospital. He said the helicopter had been continually updated over the years.



"The only original thing left is a panel with our name on it," Meadors said.



He said the helicopter averaged about 600 flights a years. All the maintenance was up to date and the helicopter exceeded the minimum standards, Meadors said. It was they only helicopter used by the hospital.



Hospital president and CEO Gary Kaatz said officials are still figuring out what to do about the transport program. REACT was started in 1987 using a helicopter from the Illinois Department of Transportation based at the Rockford municipal airport, officials said.



A few years later, REACT acquired the helicopter that crashed Monday night.



Kaatz called the three crew members "heroes."



"Our hearts are with the families of Jim, Karen and Andy," he said. "We ask for the community to join us in keeping them in our thoughts and prayers."



All three were natives of the Rockford area. Hollis grew up in Rockford. Dillow grew up on a farm west of town. Olesen had been a Rockford resident, had left and come back.



Kaatz said the hospital was cooperating with the National Transportation Safety Board. "Our focus will be on identifying the needs of those families and doing everything possible to help them get through this awful tragedy," he said.



On the hospital's Facebook page, hundreds of people, many of them paramedics and other emergency responders, offered their condolences to the victims' families.



The nurses and pilots who work in air ambulances are among the best trained in their fields, said Stephen Richey, a former flight respiratory therapist who lives in Indianapolis.



Pilots must be able to land on improvised landing sites on short notice, and the flight nurses on board often must deliver advance medical care to critically injured trauma patients.



The work draws those with years of experience and a deep commitment to helping patients, Richey said.



"You'll never find a more dedicated group of professionals in your entire life," Richey said.



Medical flight crews also face daily risks. Richey became an aviation safety researcher after losing several friends in crashes, he said.



In October 2008, a medical helicopter crashed after striking a wire attached to a radio tower in Aurora, killing three crew members and a 1-year-old girl.