Twitter officially declared it was a news app rather than a social network back in April when it changed categories in the iOS store. Now, to show it's serious about the classification, the site is experimenting with breaking news notifications.

Twitter has been testing the feature on a limited number of users these past few months, and now appears to be expanding it to a wider audience. The company confirmed to Buzzfeed that breaking news alerts are "part of a larger test notifying users about real-time content appearing on the platform."

Some people reported receiving breaking news alerts about the truck that crashed into the Berlin Christmas market yesterday. Many users said it was the first time they had received such notifications, which link to Twitter's Moments tab where the story is summarized through curated Tweets.

The site uses algorithms to decide which notifications a person receives. While the breaking news alerts cover major stories such as Fidel Castro's death, topics also include sports and entertainment items.

The breaking news alert feature is still in the testing phase, so there's no guarantee it will roll out to all users. And you can always turn it off if you already get enough notifications on your device.

In a separate piece of Twitter news, the site will no longer be showing search results in reverse chronological order; instead, they will be ordered based on relevance. The same relevance-based ordering has been a part of users' timelines since the start of the year, though it is possible to opt-out.

Precisely what's relevant to each person is determined by their behavior on the platform using a machine learning model. Users weren't happy when the ordering change came to their timelines, but there's likely to be less objection toward its used in the search results.