St. Thomas sophomore Alexei O’Brien witnessed a Minneapolis-bound Megabus catch fire Sunday afternoon just outside of Chicago.

“It started as a fire, but then it actually — the bus blew up,” O’Brien said.

The bus was carrying about 40 passengers, but authorities say no one was injured.

O’Brien, who was in Chicago for the weekend visiting family and friends, said he first noticed something was wrong after waking from a nap to the smell of burning rubber. Even after unloading from the bus on the side of the road and seeing smoke, he didn’t think it was a big deal.

“People were getting off the bus to get some air, and then we started to get our stuff off to switch buses, but then the luggage compartment was being filled with black smoke,” O’Brien said. “When there was smoke, I thought nothing of it. I was like, Oh, the bus is on fire. We should probably get as much luggage off, until there was too much smoke that we couldn’t even go into the compartment.”

Ten to 15 minutes later the bus exploded and was engulfed in flames sealing the fate of O’Brien’s and nearly everyone else’s luggage. O’Brien said he was the last one by the side of the bus, about 20 feet away, just prior to the explosion.

“I told a guy, ‘You have to get away from here, this is not safe, you have to go farther away,’” O’Brien said. “I turned around and it was engulfed in flames. And then I was just scared … I got mad because I realized all my books and school work were in my luggage, and that burned and blew up with the bus. I managed to grab my backpack and that was it.”

Despite the loss of his luggage, O’Brien and his family expressed immense relief that all passengers and the driver escaped unharmed.

“I am just grateful,” he said. “It could have been much much worse. People could have been hurt. People could have died. It was not the best scene.”

The passengers continued their journey to Minnesota on another Megabus — one that O’Brien said will be his last.

The cause of the fire is still under investigation.