A section of highway in southern Illinois was shut down on Thursday afternoon after a Megabus crashed into a concrete pillar that holds a bridge above Interstate 55. State police blamed the crash on a flat tire, which caused the driver to lose control, according to the Chicago Tribune.

The crash took place in the town of Litchfield, which is about 60 miles north of St. Louis. Emergency crews used ladders to reach into the bus to rescue people sitting on the upper deck of the two-story vehicle. At least 20 ambulances and two helicopters have responded to the scene although it's unclear exactly how many people were injured.

The Tribune reported that at least one person was wheeled into an ambulance on a stretcher and other travelers were being treated by paramedics on the side of the road. Local affiliate KSDK.com is reporting that St. Francis Hospital in Litchfield has received at least nine patients already but more were on the way. Memorial hospital, which is also nearby, had two patients in their care and were expected at least three more.

Social media exploded with the news of the crash on Thursday in part because the blue and yellow buses are so often seen driving around cities and rural highways all over the country. The service is best known for its cheap fares and for being one of the go-to ways to travel for college students around the holidays.

One passenger on the bus said the bus o was scheduled to stop in St. Louis followed by Columbia and them Kansas City.

In September of 2010 four people were killed outside Syracuse, New York when the Megabus they were riding on struck a low clearance bridge. WKTV.com reports that the double decker bus was too large to clear the structure.