Yelp and Facebook can be great promotional tools for small businesses looking to get footholds in crowded markets. They can also turn into raging battlefields teeming with tens of thousands of angry Americans.

That seems to be the case for the Red Hen, the upscale farm-to-table eatery in Lexington, Virginia, that booted White House press secretary Sarah Sanders on Friday.

On Monday morning, President Donald Trump led the charge on Twitter, blasting the Red Hen for its allegedly "filthy canopies, doors and windows." But the backlash went into high gear on Yelp, where detractors swarmed the restaurant's public listing and flooded it with one-star ratings and politically charged comments.

Yelp was apparently forced to lock down the page, concealing the most recent ratings and reviews with a graphic that said "Active Cleanup Alert." The activity on the page was being "monitored" by the Yelp support team, a banner at the top of the page said.

An "Active Cleanup Alert" appeared on the Yelp page for "The Red Hen" in Lexington, Virginia. Yelp

"While we don't take a stand one way or the other when it comes to these news events, we do work to remove both positive and negative posts that appear to be motivated more by the news coverage itself than the reviewer's personal consumer experience with the business," Yelp said in the message explaining the alert.

The restaurant's Facebook page was also inundated, with some commenters criticizing the eatery for kicking out Sanders and others praising it for taking a stand against the Trump administration over its "zero tolerance" immigration policy.

The most recent post on the page, a May 10 announcement about coq au vin (a French braised chicken dish) being added to the menu, was bombarded with more than 30,000 comments as of Monday afternoon.

Small businesses that find themselves in the news for whatever reason can now expect a digital deluge on their social media and business pages, some of which are the primary online presence for independently owned restaurants and bars. Yelp listings, for example, are among the top search results on Google, and the user-written reviews sometimes rival those of professional critics.

The phenomenon is not limited to politics. When two popular YouTube video creators quarreled with a bar in Cleveland, the establishment's Yelp page was deluged and some of its staff received death threats.

As of Monday, the Red Hen was already deep in the grip of online hysteria. Conspiracy theorists who had erroneously pegged a Washington pizza parlor as the site of a child sex slave operation were already showing signs of zeroing in on the Red Hen's staff.

so looks like it took just 24 hrs for the Red Hen to get Pizzagate'd. jesus. pic.twitter.com/doJfh0mPTi — Charlie Warzel (@cwarzel) June 25, 2018

The furor can also end up hitting other businesses by mistake. An Italian restaurant in Washington that is also named the Red Hen was caught up in the controversy.

That establishment, a reported favorite among local politicos, was hit with a flurry of criticism online, according to its owner, Mike Friedman.

"We woke up on Saturday to a storm on social media," Friedman said, adding that the Red Hen in Virginia reached out to explain what had happened.

"We [received] threats to the business, death threats, and some vandalism," Friedman added.

The onslaught got so intense over the weekend, Friedman said, that "I have had to remind myself the last few nights that we didn't actually do anything."