Taco Bell made a bold move today to grab the attention of hungry millennials. It darkened its social media pages (even appearing to wipe out its 1.4 million Twitter followers and erase all previous Facebook posts) to spotlight a single message: Customers can now order tacos, burritos and chalupas from the chain's new mobile app.

The Mexican fast-food chain, with the help of DigitasLBi, just launched an iPhone and Android app that lets consumers build customizable orders, find nearby locations, check out with a credit card and save favorite items. The app also includes a feature dubbed "rotate to reorder," which pulls up past orders when a phone is held horizontally.

Once an order is made, consumers can pay with a saved credit card, debit card or gift card. The app then uses location services to detect and check-in consumers when they are near a store, where they can skip the typical lines.

While a number of big-name chains like McDonald's, Wendy's and Burger King already offer mobile ordering, Taco Bell claims to be the first to roll it out for both drive-through and in-store orders.

Going Dark and Purging Followers

Earlier today, Taco Bell killed its Twitter, Tumblr and Facebook presence to promote the new app. The social sites now feature a single post with the hashtag "#onlyintheapp," essentially redirecting followers to the app.

Taco Bell has 1.4 million Twitter followers, but appears to have locked its main account under another name for the duration of the stunt. In its place, Taco Bell set up another account that has gained about 2,000 followers so far.

The brand's 10 million Facebook "likes" remain, though all previous brand posts have vanished.

While going dark will surely build some buzz around the app, it also cuts Taco Bell's chances of chatting back and forth with fans on social media.

The brand kept its Instagram posts, but it queued up nine images in the app's grid view to read, "The new way to Taco Bell isn't on Instagram. It's #onlyintheapp." Similar content was also posted on Snapchat and Vine.

A 15-second national TV ad (created by Deutsch Los Angeles) also supports the launch of mobile ordering with a similar call to action prompting app downloads.