Officials say a packed double-decker Megabus traveling from Chicago to Kansas City blew a tire before slamming head-on into a concrete bridge support pillar on an Illinois interstate.

Illinois State Police Trooper Doug Francis says he has no reports of fatalities but can't immediately confirm the number of injuries from the Thursday wreck of the discount charter bus.

Television helicopter footage shows numerous emergency vehicles surrounding the bus and rescue crews climbing ladders to reach inside its smashed front end. Some passengers are being tended to along the side of Interstate 55.

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