BUTTE, Mont. (AP) âÄî Investigators will examine whether a single-engine turboprop plane was overloaded when it nose-dived into a cemetery and killed 14 people on board who were heading to a retreat for the ultrarich for a ski trip, a federal official said Monday. The plane was likely designed to carry a total of 11 people, including two pilots, Mark Rosenker, acting chairman of the National Transportation Safety Board, said at a news conference. Officials said seven adults and seven children were killed in the crash Sunday; a relative said there were two 4-year-olds and the other children were ages 1, 3, 5, 7 and 9. “It will take us a while to understand,” Rosenker said. “We have to get the weights of all the passengers, we have to get the weight of the fuel, all of the luggage.” Rosenker said it was possible that a very small child would be on the lap of an adult. “We are going to have to try to understand how and why there were an additional three people (over the assumed configuration) on the aircraft,” Rosenker said. Some luggage was retrievable for weight and measurement analysis, he said. Relatives of the victims said they had been traveling to the Yellowstone Club for a skiing vacation. The club, near Yellowstone National Park, is a millionaires-only resort that counts former Vice President Dan Quayle and Microsoft founder Bill Gates among its 340 members. “We were going on a vacation with all the grandkids,” said Irving M. “Bud” Feldkamp, who lost two daughters and their families in the crash. “They were all excited about skiing.” Feldkamp leased the airplane that crashed. He said he, his wife and another daughter had driven to Montana for the vacation. “We were at the entrance to the Yellowstone Club when I got a cell phone call” from my nephew, Feldkamp said. “He saw it on CNN. He said, ‘Nobody survived.’ And we knew it was our plane.” Feldkamp spoke with The Associated Press shortly after he and other relatives of the victims spent about 45 minutes at the crash site. Feldkamp said the victims were Erin and Amy Jacobson of St. Helena, Calif., and their children, 4-year-old Taylor; 3-year-old Ava, and 1-year-old Jude; Michael and Vanessa Pullen of Lodi, Calif., and their children, 9-year-old Sydney and 7-year-old Christopher; Brent and Kristen Ching of Durham, Calif., and their children, 5-year-old Heyley and 4-year-old Caleb; and the pilot, Buddy Summerfield. Feldkamp said Amy Jacobson and Vanessa Pullen were his daughters, and that Brent Ching was the son of club member Bob Ching. On Monday, snow fell gently as investigators gathered before dawn at the scene of the crash in Holy Cross Cemetery. The turboprop plane left Oroville, Calif., headed for Bozeman, Mont., but changed course to Butte, where it crashed about 500 feet short of Bert Mooney Airport. The pilot gave no indication to air traffic controllers that the aircraft was experiencing difficulty when the pilot asked to divert to an airport in Butte, Rosenker said in an e-mail earlier in the day. Rosenker said there was “no indication of any trouble when the diversion was requested to ATC (air traffic control).” Officials said the plane didn’t have a cockpit voice recorder or flight data recorder that investigators use to help determine the cause of an accident, and the craft wasn’t certified to carry commercial passengers. Like thousands of small airports across the country, the Butte airport doesn’t have radar control. It was the worst plane crash in America since a commuter plane last month fell on a house in a suburb of Buffalo, N.Y., killing all 49 passengers and a man in the home. Before the Buffalo crash there hadn’t been an accident involving a commercial airliner in the U.S. in which there were fatalities in more than two years. A witness said the plane jerked to the left before nose-diving into a cemetery. Kenny Gulick, 14, told CBS’s “The Early Show” on Monday that he thought he was watching a stunt plane because the pilot was making so many turns. “He jerked the plane to the left too quickly and lost control of it, but that’s just my guess,” said Gulick. “And all of a sudden it went into a nosedive. I noticed the pilot trying to pull up but he was extremely low to the ground and he didn’t pull up in time.” With no radar at the Butte airport, a pilot approaching would normally switch to a radio frequency used by aircraft coming in and out of Butte to find out if there were any other aircraft in the area. Then the pilot would use visual flight rules and follow the procedures for landing at that airport. The plane was registered to Eagle Cap Leasing Inc. in Enterprise, Ore., said FAA spokesman Mike Fergus. Bud Feldkamp is president of the company, and of Glen Helen Raceway in Southern California. The plane was a Pilatus PC-12. In Switzerland, Markus Kaelin, executive assistant to the chairman of Pilatus Aircraft, said the company had no comment. Steve Guidoni, of Butte, was driving by with his wife when he saw the crash. “It just went straight into the ground. I went over there to try to help. I thought maybe I would pull someone out of the fire.” Guidoni said he saw luggage and seat cushions lying around, but no bodies. He said the biggest piece of the plane was the size of a kitchen table. “You wouldn’t even know a plane was there,” he said. Nick Dipasquale, 19, was working at a gas station across the street. “I heard a loud bang,” he said. “It sounded like someone ran into the building.” The plane took off from Brown Field Municipal Airport in San Diego on Saturday evening and flew to Redlands, Calif., about 100 miles north, said Rachel Laing, a spokeswoman for the city of San Diego. It then left Sunday morning for Vacaville, Calif., according to Flight Aware, a Web-based service that tracks air traffic. From there it flew to Oroville, Calif., and on to Butte.