UPDATE: It’s all back up. as of 11:45 am ET, making the downtime total nearly 5 hours. No explanation on what caused the outage.

ORIGINAL ARTICLE: If you tried to check-in on Foursquare when you arrived at work this morning, you were probably disappointed. Foursquare has been down since around 7am ET.

The company has confirmed the outage on their status blog

The site is down and we’re investigating now. Will update as soon as we have more information. Thanks for your patience!

About an hour after that, Foursquare posted this update:

We’re working to identify the cause of the outage. We’ll have another update soon.

And just five minutes ago (10:30am ET), they said that they’re “continuing to work on things.”

The outage is affecting both their mobile apps and foursquare.com.