It rattled homes and the nerves of people living in Lafayette, but the questions about a late night boom linger long after it occurred.

The buzz Monday at the Lafayette Brewing Company and all around the city was about what happened the night before.

"It was very weird. Very weird," said Jennifer Russell.

"It was more of a solid thud, it wasn't so (explosion sound), it was more of a 'boom,' then nothing happened," said Jim Surface.

Around 11 p.m. Sunday, there was an explosion, or something like it.

"It was a sudden, 'Wow, it's there, it's loud' and then it's over. Almost as quickly as it started, it was done," Russell said.

The calls came pouring into 911.

"Yes. It's very weird," said Lafayette Police Lt. Brian Gossard.

But officers who searched citywide couldn't find anything. No car accidents, no fires.

So what was the source of the sound that could be heard all over Lafayette? Police say there were no explosions last night. They checked with Duke Energy, factories and airports and found nothing.

So what was it?

"We don't really know what the cause was and today, nobody's reported anything suspicious," Gossard said.

The lack of an explanation is unsettling to some.

"Yeah, that's kind of worrisome, just because it seemed to be so close to where I lived, that not knowing what it was, I was very curious and now I'm even more so," Russell said.

Others could care less.

"I don't scare easy. I'm a little guy. I'm 5'4", so if I was scared of big things, I'd be scared of everything," Surface said.

The case will likely be closed without a resolution.

"If nothing comes in, I guess we'll chalk it up to one of those things we'll never know about," Gossard said.

A mysterious sound in the night that inexplicably came and went.

"Just another crazy day in Lafayette, Indiana," Surface said.