An overseas organization allegedly affiliated with the Islamic State group successfully hacked the website of a New Jersey school district Monday by posting a recruitment video. The FBI was investigating the incident that affected hundreds of school district websites across the United States.

In the early-morning internet assault, a group that calls itself "Team System DZ" reportedly hacked School Desk, a company that hosts school district web pages, and wiped all original content with a recruitment video. The attack on the school’s hosting website was among 800 sites affected Monday morning, according to reports.

The attack occurred around 4.a.m., according to an alert posted on the District’s website. Officials reclaimed the school’s site just three hours after the initial hack. The group hit a slew of other school district sites in Alabama, Florida and Georgia.

"For about two hours, our websites displayed an ISIS-sponsored YouTube video," the district said in a message posted to its website. "Around 6 a.m., the hacked page was brought down and by about 7 a.m., full functionality and control were restored." 

The ISIS-affiliated video posted to the school sites featured images of former Iraqi leader Saddam Hussein with a message written in Arabic that translates to, "There is no God but God. Mohamad is the profit of God," NBC News reported.

"The FBI and investigative agencies are looking into the matter," the alert continued.  "At no time was confidential student or staff data compromised. The internal computer and data systems within the district were completely unaffected. Everything that happened occurred at the web host's companies server farms in Atlanta, Georgia and Florida."

School Desk uses a system known as CloudFlare against hacks and has built-in firewalls for added protection, founder Rob Frierson told The Star-Ledger. The company restricts all site traffic outside of the U.S. The hacker likely used a VPN service to gain access to the site, Frierson said.

School officials notified the FBI after they confirmed the Monday attack, Frierson added. School Desk said in a statement that it added extra layers of security to its site and has conducted a probe of the breach.

"Team System DZ" also attacked a Washington-based government website in July, CNN reported. A screenshot provided by the site said that the group posted a message that read: "You will be held accountable, Trump, you and all your people for every drop of blood flowing in Muslim countries."