LAS VEGAS, Nev. -- By Frank Curreri and Shaliz Koleini, FOX5 News

Authorities are still probing why a gunman walked into New York New York casino after midnight Friday, randomly opening fire on gamblers and injuring four people.

Police: Shooter Wanted Suicide By Police

The chilling outburst sent patrons and workers scattering for cover inside of the packed casino, witnesses told FOX5 News, but security personnel and patrons quickly and courageously sprung into action, tackling the man and subduing him. Police said the brave bystanders included three off-duty out-of-town police officers and two military personnel.

Las Vegas police rushed to the scene soon after the 12:45 a.m. incident and immediately took the man into custody. Investigators have identified the suspect as 51-year-old Steven Zegrean of Las Vegas, a Hungarian immigrant and former house painter. Zegrean's family members said he has been making threats toward them in recent weeks. Police said Zegrean was emotionally distraught and that the shooting has nothing to do with terrorism.

Zegrean faces felony charges including four counts of attempted murder, four counts of battery, burglary, conspiracy to commit murder and 16 counts of discharging a firearm into an occupied structure.

Witnesses told FOX5 News they saw a man walking prior to the shooting and he was silent and did not exhibit any unusual behavior. Then, without warning, the man unleashed a hail of gunfire. Chaos briefly ensued, with people running through the casino and hiding behind machines and tables.

"It absolutely did appear to be random," said Marc Joseph, a deputy chief for the Metropolitan Police Department. "(There) did not appear to be any single target."

Jade Jacobson, a Floridian in town on vacation, said the gunfire prompted pandemonium. Jacobson's cousin was wounded in the leg, but has been treated at the hospital and released. A 13-year-old from Van Nuys, Calif., who was wounded in the ankle, said he thinks he heard 10 or more shots.

Police said Zegrean possessed a handgun and fired 16 shots from a balcony overlooking the casino floor. Four people were shot, one of them grazed by a bullet. Another woman suffered bruises after being trampled by fleeing crowds, police said. None of their injuries appear to be life-threatening, police said.

Despite the disturbing act, the casino and hotel were not evacuated and officials did their best to resume with business as usual. There were some obvious exceptions, however: Officials closed off a small portion of the casino where police conducted their follow-up investigation. Authorities also closed down the bridge that connects MGM Grand casino and hotel with New York New York, though that walkway has since been re-opened to the public.

Police have not yet released the identity of the suspect. Stay tuned to FOX5 News and FOX5Vegas.com for more on this developing story.