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ORLANDO (CBSMiami) – The Medical Examiner’s Office began the grim task of removing the victims from inside an Orlando nightclub following a mass shooting that left at least 50 people dead.

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Meanwhile, the families of the victims were waiting at an Orlando hotel Sunday night to find out if their loved ones were among those dead.

The shooting, which took place at Pulse Orlando, a nightclub that describes itself as the “hottest gay bar in Orlando,” left an additional 53 people injured.

An FBI spokesman called the incident a domestic act of terrorism.

“We consider this an act of terrorism. Absolutely we are investigating this from all parties perspective as an act of terrorism,” said Danny Banks of the Florida Dept. of Law Enforcement.

Law enforcement sources told CBS News that the identity of the shooter is 29-year-old Omar Mateen, a U.S. citizen from Port St. Lucie.

Authorities searched his home after the attack, determining that there were no explosives inside. Residents were let back into their homes late Sunday after a temporary lock down of the complex.

Photo of Omar Mateen, suspected shooter in Pulse Orlando massacre. (Source: CBS News)

Photo of Omar Mateen, suspected shooter in Pulse Orlando massacre. (Source: CBS News)

This now ranks as the deadliest mass shooting in U.S. history.

Orlando Shooting Just The Latest In U.S.

Mateen was killed after a gunfight with police inside the club, according to authorities. He was said to have been carrying an assault-type rifle and a handgun.

“It was just one after another, after another, after another,” said witness Chris Hansen. “After everybody was out, shootings were still going and the cops were yelling, ‘Go, go, clear the area, clear the area!'”

Orlando Police Chief John Mina said that a loud noise reported near Pulse Orlando was a “controlled explosion.”

According to Mina, Mateen exchanged gunshots with an officer who was working at the club before going back inside and taking hostages around 2 a.m.

During the shooting, Mateen called 911 and gave his full name before he pledged allegiance to ISIS.

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About three hours later a SWAT team went inside to rescue the hostages which is when Mateen was killed during a gunfight with those officers.

An Orlando Police officer was hit by a bullet during the gunfight that killed Mateen. The Kevlar helmet that the officer was wearing saved his life.

Orlando Mayor Buddy Dyer said that it will take authorities time to identify the 50 people who were killed inside the nightclub, as well as the 53 injured that were transported to local area hospitals.

The majority of those taken to the hospital are considered in critical condition.

It was estimated that around 320 people were inside the nightclub when it opened on Saturday night.

Authorities have since said  that they are “leaning towards Islamic terrorism” as the motive for this shooting.

At 9:15 a.m. on Sunday the White House released the following statement:

“The President was briefed this morning by Lisa Monaco, Assistant to the President for Homeland Security and Counterterrorism, on the tragic shooting in Orlando, Florida. Our thoughts and prayers are with the families and loved ones of the victims. The President asked to receive regular updates as the FBI, and other federal officials, work with the Orlando Police to gather more information, and directed that the federal government provide any assistance necessary to pursue the investigation and support the community.”

Pulse Orlando posted on its own Facebook page around 2 a.m.: “Everyone get out of pulse and keep running.”

Around 6 a.m., the club posted an update: “As soon as we have any information, we will update everyone. Please keep everyone in your prayers as we work through this tragic event. Thank you for your thoughts and love.”

Florida governor Rick Scott also released a statement on Sunday morning:

Our thoughts and prayers are with the victims, families and all those affected by this horrific tragedy.  We are a strong and resilient state and we will devote every resource available to assist with the shooting in Orlando.  Our state emergency operations center is also monitoring this tragic incident.  I have been in constant communication with Orlando Mayor Buddy Dyer, Orange County Mayor Teresa Jacobs and state and local law enforcement this morning. I would like to also thank all the first responders who quickly came to assist and help those in need.

Governor Scott was in Orlando meeting with law enforcement and local officials.  He declared a state of emergency for all of Orange County early Sunday afternoon.

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Pulse Orlando is located less than four miles from where Christima Grimmie, known for her appearance on “The Voice” was shot and killed while signing autographs for fans following a performance.