Police and Orlando city officials said 50 people are dead and 53 are hospitalized after a gunman opened fire in a gay nightclub early Sunday.
Here is what we know so far:
PHOTOS: Mass shooting at Orlando nightclub
• A gunman opened fire in a gay nightclub: It began around 2 a.m. Sunday as a gunbattle between a man and a police officer who was working at the Pulse nightclub near downtown Orlando, Police Chief John Mina said at a news conference. It became a hostage situation and there was a three-hour standoff until a police SWAT team burst through a wall to rescue those inside.
About 320 people were in the club, police said. Some people escaped through the back of the club, while others were trapped inside.
A federal law enforcement official told USA TODAY the suspect had been identified as Omar Mateen of Port St. Lucie, Fla.
• Three-hour standoff unfolded: Officers from multiple departments arrived at the scene after the shooting. A bomb squad was called in, and before 5 a.m. officers conducted a controlled detonation. Police used an armored vehicle to break through a wall at the nightclub, then SWAT team members exchanged gunfire with the suspect. He was shot and killed. Mina said the suspect was armed with a handgun and an assault rifle.
Officers rescued at least 30 hostages from the club.
• Fifty victims found dead: At a late-morning press conference, police and Orlando city officials said 50 people were dead and another 53 people were hospitalized. It is unclear what the condition of those victims are. Police had initially said that at least 20 people were dead but found far more were dead inside the club.
Nine police officers were involved in the shooting incident and one was injured. Police said it appears a Kevlar helmet saved the life of the officer, who suffered facial injuries.
• Terrorism suspected: Police described the mass shooting as a "domestic terror incident." Authorities are investigating whether the incident was the work of Islamic terrorism, and the FBI is investigating.
When asked whether the shooter had ties to a Jihadist terror group, FBI Special Agent Ronald Hopper said during a news conference that "we do have suggestions that that individual may have leanings toward that, that particular ideology. But right now we can't say definitively so we're still running everything around."
Sen. Bill Nelson, D-Fla., told reporters that there appears to be connections to ISIL, though the FBI has not yet confirmed the suspect's motives.
• Suspect had "suspicious device": Witnesses reported seeing a bomb in the gunman's possession, but police did not confirm that detail. Police did say the gunman was armed with an assault rifle, a handgun and an unidentified "suspicious device." A bomb squad responded to the scene and conducted a "controlled explosion," police said.
• Shooting suspect's father: Mir Seddique told NBC News that the shooting "had nothing to do with religion" and that his son got angry when he recently saw two men kissing in Miami.
• Other threats: Authorities said they had no indication of any other threat in Florida or elsewhere in the nation. However, the city of Orlando and Florida state officials declared states of emergency.
• Hotlines for family members, tips: Police said they are focusing on identifying the victims. Family members who are trying to locate relatives can call 407-246-4357. A family assistance center has been set up at the Hampton Inn at 43 Columbia Street in Orlando. The FBI has asked anyone who was at the club before the shooting and anyone with tips to call 1-800-CALL-FBI ( 1-800-225-5324).