Authorities in Florida have identified the shooter at the Pulse nightclub as Omar Mateen, a US citizen from Afghanistan who lived in Port St. Lucie, Florida.

No further information was released about the suspect.

At this stage of the investigation, it is not clear if the motive was Islamic terror. The Islamic State and other terrorist groups have yet to claim responsibility.

Police, however, are investigating the mass shooting as an act of domestic terror.

Police: Investigating Orlando nightclub shooting as an “act of terrorism.” https://t.co/ZdaJMtkE0q https://t.co/PBpwOYKMGE — ABC News (@ABC) June 12, 2016

Last week the “United Cyber Caliphate” posted a list of Americans it said would be killed. The list included names, addresses and emails of thousands of civilian Americans, including more than 600 people in Palm Beach County and on Florida’s Treasure Coast.

Former FBI agent turned lawyer Stuart Kaplan told CBS-12 on Wednesday the list would “create some hysteria.” He predicted it would inspire so-called lone wolf attacks.

“If in fact a sympathizer gets ahold of this list and is readily able to identify you as being his neighbor and, then, decides (because they’re a sympathizer) to go out and do something horrific to you, there is no way to calculate the potential or to prevent that,” Kaplan said.

Speculation is widespread on Twitter today the attack was carried out by the Islamic State.

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