For the first 5 seconds, we didn't really pay attention (sometimes when large trucks go by or they're moving large furniture in the office, the floor vibrates), but when it lasted for more than 10 seconds, we kind of started thinking, "um...what's going on?"
When other people started peeking out of meeting rooms and cubicles, asking if anyone else was feeling it, we knew something was happening.
Yep, Toronto (where I am) felt tremors. Apparently, there was a 5.0 magnitude earthquake close to Canada's capital, Ottawa and the quake was felt in Ontario, Quebec and parts of northern US.
Eeek! Pretty scary stuff.
What's even scarier is that almost within minutes, people were online hawking t-shirts, buttons and other "memorabilia" centred around "Canada's 2010 earthquake". I think it's really silly (and kind of stupid and tempting fate) to buy anything that says you survived a 2010 earthquake when there's still over 6 months left in 2010, don't you?