One person was killed and at least 32 injured Thursday afternoon when a double-decker Megabus slammed into a concrete pillar along Interstate 55 in southern Illinois.



The bus was traveling from Chicago to Kansas City, with stops in St. Louis and Columbia, Mo., the company confirmed. The wreck happened near Litchfield, Ill., at mile marker 57, about three miles south of the Carlinville exit and about 55 miles northeast of St. Louis.



The fatality was a female passenger sitting near the front of the bus, a state official told NBC Chicago. The bus driver was among those injured. He was taken to a hospital, but his injuries were not believed to be life-threatening.



Megabus said there were 81 passengers booked for the trip but Illinois State Police said just 64 were on board. The total number of passengers is expected to remain fluid through Thursday evening.



Trooper Doug Francis said "several" of the passengers were in critical condition. Thirty-three passengers were taken to either St. Francis Hospital in Litchfield and Memorial Medical Center in Springfield. Five people were transported by medical helicopters, he said.



Memorial Medical Center spokesman Michael Leathers said its trauma center 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, 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 were also treating patients.



On her Facebook wall, Lisa Hepburn-Kovco of Chicago said her husband, Joe, was on board the bus when it blew a tire.



"Joe was on his way for Marine Corp reunion to Kansas City Missori [sic] and the bus had a blow out and hit a concrete barrier. He is ok. Hit his head has a bad shoulder injury and some cuts but is doing ok. Please prey [sic] for everyone one the bus," she wrote.



Hepburn-Kovco said she could hear people screaming and crying while she was on the phone with her husband.



The front of the bus was extensively damaged and debris was strewn about the road. First responders were seen using ladders to gain access to the bus. Multiple people could be seen strapped into gurneys, some completely covered by sheets.



Francis said five helicopters, 30 ambulances and seven fire departments responded to the wreck.



"Safety remains our number one priority. We can confirm that the vehicle involved in the accident was manufactured in 2011 and had passed a full preventative maintenance check within the past week," company spokeswoman Amanda Byers said in a statement.



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 interstate was shut down in both directions between mile marker 52 and mile marker 60, ISP said.



Family members of passengers are asked to contact the Litchfield Community Center, at 217-324-3032, or the Illinois State Police, at 217-324-4900 (extension 223), for updated information.



The scene is near where a school bus returning students from a field trip rammed the back of a tractor-trailer truck stopped in traffic May 14, injuring 11 students, the St. Louis Post-Dispatch reminded.



Thursday's fatal accident was the first for the Chicago-based company since four passengers were killed in September 2010 when the driver of a double-decker Megabus smashed into a low bridge outside downtown Syracuse, N.Y. The driver was acquitted earlier this year of homicide in the deaths.



Megabus operates double-decker buses on scheduled routes to more than 80 cities. It has served more than 19 million passengers since its launch in 2006, the company says on its website.



Federal transportation officials were been notified of the crash Thursday.



"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. [View the story "Megabus Crash Near St. Louis" on Storify]