People everywhere commemorated the anniversary of the 9/11 attacks Wednesday. (Via National Park Service)

Many of them took the social media route, like the "never forget" hashtag on Twitter. (Via Flickr / slagheap)

Brands got involved, too — and the criticism came quickly as some marketing messages looked like attempts to capitalize on the tragedy.

BuzzFeed showed this screengrab of an AT&T tweet, calling it "the tackiest 9/11 memorial on the Internet."

Fast Company says, "Within minutes a maelstrom of angry tweets began pouring in," causing AT&T to issue this response: "We apologize to anyone who felt our post was in poor taste. The image was solely meant to pay respect to those affected by the 9/11 tragedy."

AT&T also posted the image to Facebook. It has since been removed from the company’s social media accounts.

Other brands put their 9/11 tributes out there without causing the same stir AT&T did — like American Express, which shared an image of One World Trade Center sans any self-promotion in the picture.

Still, a writer for Death and Taxes says sending the message to begin with is tantamount to tooting one's own horn: "The thing is, the brand name itself is an advertisement for its product. So everything a brand writes … is still a tacit advertisement for the said product."

Advertising-industry publication Digiday asked whether brands should even be tweeting about 9/11: "One would think that the most respectful thing a brand could do would be to not say anything at all, unless the brand's employees or customers were in some way directly [affected] by 9/11."

So, when would it be OK? Digiday specifically referenced a tweet from the American Red Cross, which read simply, "Today, we remember #september11."

That tweet, as you might expect, drew only positive responses. The same can't be said for one from the Los Angeles Lakers, who Ad Age said "seemed to realize they were treading on thin ice" by tweeting a Kobe Bryant photo with the #neverforget hashtag as a graphical overlay. The Lakers quickly deleted the tweet.

In an op-ed for Mashable, Todd Wasserman suggested brands simply avoid participating in certain holidays or anniversaries of tragedies.

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