CHICAGO — At first, the passengers aboard the Southwest flight trying to land amid heavy snow at Midway International Airport thought it was a normal landing. Then there was a bump — and the plane was in the street.

"There was a bump. I saw snow rush over the wing, then there was a big bump," said passenger Larry Vazzano, 54, of Baltimore. "I braced myself on the seat in front of me."

The jetliner skidded across the runway, slammed through a fence and struck vehicles in the street, hitting one and pinning another beneath it. A 6-year-old boy was killed, and at least 10 others were injured, authorities said.

The crash closed the airport, Chicago's second largest after O'Hare International. Airlines and authorities said it planned to reopen this morning.

Flight 1248 from Baltimore touched down at Midway International Airport around 7:15 Thursday night. Although the airport had about 7 inches of snow, aviation officials said conditions at the time were acceptable.

Mike Abate, 35, of suburban Milwaukee, said he could see from the plane that a man was carrying an injured child and that other people were taken away in an ambulance.

"We were safe on the plane," Abate said. "The toughest part was to realize that someone was under the belly of the plane."

Five crew and 98 passengers were aboard the plane, authorities said. Most were evacuated through the plane's inflatable slides in blowing snow, while others used stairs at the rear of the plane, said Chicago Fire Department Spokesman Larry Langford. The plane's nose was crushed, and a severely damaged engine was strewn on the ground, he said.

Of the 10 injuries reported, eight were on the ground and two were in the plane.

Five people, including the boy who died, were riding in the pinned vehicle and were taken to a hospital, Langford said. Two adults and two children were listed in conditions ranging from good to serious early this morning, according to a hospital hot line recording.Three victims from the other car were released and a fourth was in good condition, Holy Cross Hospital spokeswoman Michelle Boyd said. The two plane passengers were treated and released, a hospital spokeswoman said, and a tow truck driver who stopped to help plane passengers was treated for an old injury he aggravated.National Transportation Safety Board and Federal Aviation Administration officials from Washington were on their way to Chicago to investigate.Southwest CEO Gary Kelly said the plane had circled Midway for 30 to 35 minutes because of the weather and the flight traffic before it was cleared for landing on the airport's 6,500-foot runway. The airport, surrounded by homes and businesses, has shorter runways than most major airports, because it was originally built to handle smaller propeller planes. The larger ones land at O'Hare."There are no indications that there are any maintenance problems with that aircraft whatsoever," Kelly said. He said the plane had a service check Wednesday in Phoenix.James Burnett, a former NTSB chairman, said the weather would be a focus of the investigation."When you're looking at a runway overrun, it almost always involves a runway condition that's improper," Burnett told WFLD-TV. "But that's not the only thing."Snow caused trouble Thursday for travelers across the Midwest, with as much as 10 inches on the ground in some areas.The accident occurred 33 years to the day after a crash at Midway that killed 45 people, two of them on the ground.In that crash, a United Airlines jet struck tree branches about a mile from the airport, then hit the roofs of a number of bungalows before plowing into a home, bursting into flames. Eighteen passengers survived.