Updated

A packed double-decker Megabus blew a tire and slammed head-on into a concrete bridge support pillar on an southern Illinois interstate Thursday, leaving at least one person dead and more than two dozen others injured, officials said.

Illinois State Police Trooper Doug Francis said at least one person was killed in the afternoon wreck of the discount charter bus, which was traveling from Chicago to Kansas City. He didn't immediately have other details about the death.

At least four other people were flown by helicopter to a trauma center. Another closer hospital treated more than 20 other patients from the crash.

Numerous emergency vehicles could be seen on footage shot by a television helicopter flying above the bus, which sat with its crumpled front end smashed up against the bridge support as rescue crews climbed ladders to reach inside. Some passengers could be seen being tended to along the side of Interstate 55, which was shut down in both directions.

"We received a report it had blown a tire which caused it to run off the road," Francis said. "The bus did stay upright."

MegaBus spokeswoman Amanda Byers said the bus was at full capacity, carrying 81 passengers, when it crashed near Litchfield, about 55 miles northeast of St. Louis. It also was to stop in St. Louis and Columbia, Mo.

Memorial Medical Center spokesman Michael Leathers said its trauma center in Springfield, Ill., treated a total of six patients, including four who were airlifted. He said he didn't know their conditions.

Brian Reardon, a spokesman for St. Francis Hospital in Litchfield, said that hospital has treated more than 20 patients, including some who were treated and released. Reardon said others had moderate injuries, "such as bone fractures." He said two other nearby hospitals also are treating patients.

About 36 passengers were taken on two school buses from the crash site to the community center in Litchfield, said Janis Johns, transportation director of Litchfield Community Unit School District 12.

The passengers were either uninjured or mildly injured and included some children, Johns said. One woman was brought on a stretcher in the school bus. The school district sent a third school bus to the crash site, but it wasn't needed, Johns said.

"We're close to the highway. We try to help out when we can," Johns said.

The Red Cross will be notified and coolers of water will be provided, she said.

"It was very warm out there," she said, and some crash survivors were overheated.

Federal transportation officials said they had been notified of the crash.

"The National Highway Traffic Safety Administration is aware of the incident and will work with local authorities who are investigating the crash to determine if there are safety implications that merit agency action," said a statement from the agency.