Yesterday was my first time taking Megabus, a discount intercity bus service that began in 2006 and quickly gained notoriety for advertising fares as low as $1 each way. Yesterday was also the first time I had to evacuate a bus as it was catching fire.

I was just closing my eyes when we pulled over to the side of the interstate, 50 minutes into the trip from Chicago to Milwaukee. I hadn’t noticed that there was a problem, but others, like a fellow passenger, Lauren Wurdinger, said they smelled the burning coming from the bus almost immediately. The driver got out, re-entered the bus a few minutes later, and we drove on. Minutes later, we stopped again and the driver exited again; we eventually continued. Finally, he announced on the intercom that we were turning around because we had to “switch buses.”

A groan of incredulity swept through the bus. I started tweeting updates. Why would we turn around, people asked, when we were so close to Milwaukee? (It’s about a 90-mile trip.) We turned off the interstate and began heading back toward Chicago down a smaller highway. Within minutes, there was a loud bang from the back of the bus. People leapt up from their seats. Some were cursing, some got on their phones.

We pulled over and the driver got on the intercom: It’s just a flat tire, he said, and there’s no need to panic and no need to curse. He exited the bus and we all sat there for a few minutes, dumbfounded. One passenger, Kenny Wagner, said nothing like this had happened in the dozens of times he’d taken Megabus. The bus began to smoke, and as it got thicker, we evacuated.