Facebook's Instagram back up after worldwide outage

Instagram is back up for some users on Wednesday, after suffering an outage in  several cities.

The outage included  cities such as London, San Francisco and Singapore, according to Reuters.

Many users took to Twitter to complain about the outage using the #instagramdown hashtag.

The mobile app and the website, which were temporarily down, are back up with users posting pictures and videos, according to a check by Reuters.

Earlier, the app displayed an error message saying "couldn't refresh feed," while its website did not load for users.

Facebook and Instagram were not immediately available to comment.

Instagram’s co-founders resigned in the past week. The company announced on Monday that long-term insider Adam Mosseri will take over as the new head of the photo-sharing app.

The app has more than one billion active monthly users.