Here is what we know about the deadly mass shooting in Orlando, Florida.

The shooter

-- Police identified the shooter as Omar Mateen, 29. Mateen was born in New York and later moved to Fort Pierce, Florida. He is divorced and a father of one. His family is from Afghanistan. The security firm G4S confirmed to the Palm Beach Post that Mateen had been an employee of the company since 2007.

--The FBI interviewed Mateen twice in 2013 and once in 2014 due to concerns about possible links to terrorism. At the time of the nightclub shooting, however, the FBI said he was not under surveillance.

-- The gunman was seen drinking at Pulse on several occasions before he opened fire inside the gay nightclub, according to others who frequented the bar. Patrons told The Canadian Press that they had witnessed the 29-year old being escorted drunk from the nightclub several times.

-- The shooter's ex-wife told CNN on Tuesday that she wasn't sure if her former husband had any homosexual tendencies. Her comments come after reports that Mateen had tried to pick up men at Pulse.

--The shooter's current wife, Noor Salman, told the FBI that she drove Mateen to Pulse on a prior occasion, and she tried to talk him out of going forward with the attack, NBC News reports. Officials familiar with the investigation told NBC News that Salman said she was with her husband when he bought ammunition and a holster. She may face criminal charges for failing to tell police what she knew before the attack, according to NBC News.

-- The shooter’s father, Seddique Mir Mateen, said his son may have become angry when he saw two men kissing in Miami a few months ago. Seddique Mir Mateen told NBC news on Sunday that the family was not aware of "any action he is taking." He also apologized for the massacre, stating that it "has nothing to do with religion."

In a video message posted to Facebook on Monday, Seddique Mir Mateen said he didn't know what caused his son to go on a shooting rampage. "I don't know why he committed such an act during the holy month of Ramadan," he says in the video, which has since been taken down.

"The issue of homosexuality, the punishment – whatever they do, God punishes it. It is not up to God's servants."

The victims

--The attack left 50 people dead, including the gunman. Police say 39 of the victims were killed inside the club and 11 died in hospital.

-- Another 53 were wounded, many critically. On Tuesday, authorities said 27 victims were still in hospital, including six that remain in the intensive care unit.

-- The City of Orlando has identified all 49 of the victims on its website. 

-- The toll makes the shooting the deadliest in U.S. history, ahead of the 2007 shooting at Virginia tech that left 32 dead.

--In response to the Orlando shooting, Facebook activated its Safety Check feature so that users in Orlando could tell their loved ones they are safe. It’s the first time the program has been activated in the U.S.

Details of the incident

-- The shooting took place at Pulse nightclub, a gay bar located in Orlando’s South Division neighbourhood.

-- There were approximately 300 people inside the club at the time shots first rang out at about 2 a.m.

-- Investigators say Mateen was armed with an assault rifle and a handgun and opened fire on patrons before taking hostages in a washroom in the nightclub. Another group of patrons were in an adjacent washroom. According to Orlando Police, a police officer on site at the club was first to engage Mateen moments after he opened fire.

--At some point in the ensuing hostage standoff, Mateen spoke of possible bombs and explosives, and officers believed "loss of life was imminent," police said. At that point, a decision was made to act and breach the washroom.

-- An armoured vehicle was used to punch a hole in the wall, and dozens of people climbed out of the hole, police said. The suspect also came out holding a long gun and a handgun, and was killed in an exchange of gunfire.

-- Police could not say if any of the victims died by friendly fire, noting that the investigation is still ongoing.

-- The ATF, the Bureau of Alcohol, Tobacco and Firearms, confirmed the suspect purchased the firearms legally within the last week in Florida. Police say Mateen used an AR-15-type assault rifle and an unknown amount of ammunition in the shooting.

-- The ATF also said a third weapon was found in the shooter's vehicle.

-- Ed Henson, the owner of the gun store where Mateen purchased the firearms used in the massacre, said the 29-year-old passed a full background check before being given the weapons.

-- Florida Gov. Rick Scott declared a state of emergency in Orange County on Sunday. The City of Orlando also declared a state of emergency.

FBI investigating terrorist links, motives

-- FBI Director James Comey said Monday that the gunman made three 911 calls from inside the club, during which he pledged allegiance to the Islamic State terror group. Mateen also said he was perpetrating the attack on behalf of the Boston marathon bombers, as well as a Florida man who died in a suicide bomb attack in Syria for the Al-Nusra Front, Comey said. Police said his demeanour during the calls was "cool and calm."

-- Comey also said there is no indication so far that Mateen was directed to kill based on a foreign plot, nor was it likely that he was part of any terror network. Comey said it was likely that Mateen was radicalized in part from the internet.

-- Saudi Arabia’s Interior Ministry told the Associated Press that Mateen visited the country twice for the Umrah pilgrimage, a series of Islamic rites performed by millions of Muslims each year in Mecca.

-- Comey said the FBI is trying to determine whether Mateen had been searching for other potential targets such as Walt Disney World, located just outside Orlando.

Political reaction

-- The office of the UN High Commissioner for Human Rights, Zeid Ra'ad al-Hussein, decried the "insufficient gun control" in the U.S., and urged American leaders to "live up to its obligations to protect its citizens." Al-Hussein slammed the "irresponsible pro-gun propaganda" in America that claims firearms make the country safer. He also questioned how it was possible for people in the U.S. to obtain firearms and assault weapons like the one used in the Pulse attack.

-- U.S. President Barack Obama made a public address regarding the shooting on Sunday, offering his condolences to the victims and their families. Obama also lamented how easy it had been for Mateen to legally purchase the weapons used in the attack, adding that the U.S. must “decide if that's the kind of country we want to be."

-- Obama is expected to visit Orlando on Thursday to pay tribute to the victims of the massacre.

-- Republican presidential candidate Donald Trump said “radical Islam is anti-woman, anti-gay and anti-American.” On Monday, Trump proposed a ban on “immigration from areas of the world where there is a proven history of terrorism against the United States, Europe or our allies -- until we fully understand how to end these threats.”

-- Democratic candidate Hillary Clinton vowed to make preventing lone wolf attackers a priority if elected in November and called for stricter gun control.

-- Canadian Prime Minister Justin Trudeau said he was "shocked and saddened" by the incident and offered Canada’s help in the aftermath of the shooting.

-- The U.S. government has called on the 193 members of the United Nations to proactively protect members of their LGBT communities from such acts of violence.

With files from The Associated Press