The Atlanta Police Department, UNICEF, Duke University and many other large organizations posted tweets Wednesday apologizing after they believed their Twitter accounts were hacked.

APD Public Affairs wrote in a statement to 11Alive, "We were the victim of a hack like countless other agencies and people across the world. We are taking the appropriate steps to protect all our social media accounts."

The impacted accounts all featured Twitter posts appearing on their timelines and some accounts had their profile pictures changed. Many of the hacked posts were in Turkish and featured a swastika.

The messages called the hacking a "little Ottoman slap" and said "See you on April 16" - the date of a referendum in Turkey on stronger powers for President Recep Tayyip Erodogan. A video linked in the tweet featured various speeches by Erdogan.

The hack appears to have begun with a third party app called Twitter Counter. From its Twitter account, the app company tweeted about its service being hacked and wrote that could have led to the tweets posted on other accounts.

In Atlanta, Lyfe Marketing co-founder Sean Standberry and his staff manage social media accounts for their more than 200 clients. His clients weren't hacked, but he offered suggestions for users can secure their accounts.

"Twitter Counter is a dashboard where you're able to see follower growth, engagement - which is really important when it comes down to business, understand how you're growing and what those numbers mean for you," Standberry said.

There are many third party apps Twitter users can use, some other examples are Instagram, Facebook, Yelp, and Foursquare.

When a user connects a third party app to their Twitter account, they often grant permission to the app to send tweets from their account, send direct messages or access other parts of their account and information.

While the hack featuring tweets in Turkish hit mostly large organizations, Standberry said individuals are vulnerable to similar attacks.

He said if you have concerns or hear an app has been hacked, from a computer you can easily revoke its access to your account.

"It takes like 20 seconds, just go into your Twitter settings, then go to the apps section of your Twitter profile," he said.

A screen of all the apps with access to your account is then displayed.

"And if you want to revoke one, just hit revoke access here and you will get a confirmation message," Standberry said while walking through the process with his Twitter account.

He stressed it is also good practice to scroll through the apps accessing your account from time-to-time.

"If you see something you weren't aware you signed-up for, or something that is just not needed for your Twitter profile, just go ahead and revoke access for security reasons," Standberry said.

Before adding an app it is also important to check out its background and security. Visit the company's website and see if the address begins with https://, this is one example of the company taking security measures to protect information.

"You can also look at how many users they have, how many people are using it and trust this particular source. Just a few heads up on what we're signing up for."

Twitter today acknowledged the offensive tweets posted to accounts is being investigated. The social media platform offers a support section on its website with other tips for securing your account.

One of the best measures is two-step verification. That security measure can be found in your Twitter accounts settings. It gives you an option for regaining access to your Twitter account if it is hacked and you lose control.