Authorities continued to seek answers about the gunman who carried out a shooting rampage in Orlando, expanding the investigation to include interviews with his relatives, friends and anyone else who may have had contact with him in the months before the attack.

While the FBI said they view the shooting, which left 49 dead and dozens more injured, as a hate crime as well as an act of terrorism, officials said there were "no impending charges" in the case and declined to discuss if any were forthcoming.

The FBI confirmed it had interviewed the wife of Omar Mateen, the 29-year-old gunman. Noor Salman urged her husband not to do anything on the night of the attack, said one US law enforcement official. But the bureau also tried to play down this element of the investigation, saying it was part of the larger work of piecing together the gunman's movements and motivations.

A US law enforcement official confirmed that Mateen posted threatening comments directed at the United States on Facebook before the attack. The account was later taken down.


"With respect to the wife," Ronald Hopper, an FBI assistant special agent in charge, said today, "that is only one of many interviews we're doing."

Salman has not publicly commented on the attack, and she has not been seen since Tuesday, when the Miami-based television station WSVN recorded video of the 30-year-old being escorted from her home in Fort Pierce, Florida. Her face was shrouded by the hood of her sweatshirt, and her left hand had what appeared to be a silver wedding band.

Former neighbours in Salman's home town of Rodeo, California, an area of oil refineries about 40km northeast of San Francisco, have described her as a shy and sheltered woman.

Jesus Torres, who attended middle school and high school with Salman, described her as quiet and smart, someone who hung out with the smart kids. He has remained in touch with her family since graduating from high school in 2004, and said he believed they were worried about her but did not want to pry. A neighbour told the Mercury News that Salman's "mother would always complain" that Mateen never let his wife visit her family.

Salman's romance with Mateen began online, and they were married on September 29, 2011, in an Islamic ceremony in Hercules, California, a town near Rodeo, according to friends and public records. The couple have a 3-year-old son.

Jasbinder Chahal, who has lived across the street from Salman's childhood home for the past 15 years, told AP that Salman did not appear to have lofty ambitions beyond marriage after graduating from high school in 2004.

"You know, some kids after high school, they open up the box and the world is theirs," Chahal said. "She was inside the box - just pack it up and get married."

She added: "Noor never played in the street, and the girls were never allowed to drive."

The family lives in a beige split-level home with rose bushes out front in a neighborhood that is ethnically diverse and middle class. Many of the immediate neighbours are of Indian descent.

Today, the family was holed up inside their home all day, with the shades drawn. Multiple visitors came and brought food and other household goods.

Salman accompanied Mateen at one point to buy ammunition and went with him on at least one trip to Pulse described as "reconnaissance" not long before the shooting, according to officials familiar with the investigation.

Whether she knew the purpose of that trip remains unclear.

Investigators are still working to corroborate what Salman told them during interviews, according to authorities, and will also try to determine if she suffered any abuse at the gunman's hands.

His first wife - Sitora Yusifiy, to whom he was briefly married in 2009 - said that he beat her repeatedly while they were married. How authorities ultimately view Salman's role and actions could change if she was a victim of abuse or feared for her life, officials say.

As investigators continue probing Mateen's life, they are also scouring digital forensics and are trying to reconstruct his actions dating back months. Meanwhile, evidence technicians were methodically tracing the path of the barrage of bullets that flew inside Pulse as they attempted to diagram precisely what happened.

"We're looking at everything," Hopper said.

He also said authorities had found no evidence yet that Mateen intended to target any other locations, and officials said they had "no information" about any possible surveillance at Disney nor any knowledge of Mateen patronising clubs besides Pulse.

At least two witnesses at Pulse said Mateen had previously visited the club. President Barack Obama, who is travelling to Orlando on Thursday, has called the shooting "an act of terror and an act of hate," while FBI Director James Comey said authorities were working to see if anti-gay sentiment played into the decision to attack the club.

Mateen appeared to be a very skilled shooter, according to documents released Wednesday, repeatedly scoring high marks on tests needed to obtain firearms licenses.

After opening fire on scores of people inside the nightclub, Mateen then threatened to strap explosives to his hostages and left police fearing possible booby traps even after the attacker was killed, the city's mayor said today.

No explosives or bomb vests were found, but suspicions of possible devices forced authorities to wait a "significant time" before entering the club and fully assessing the mayhem after a commando-style raid freed survivors and killed the gunman, said Orlando Mayor Buddy Dyer.

Since the attack, authorities have confronted a jumble of potential leads and loose ends. Among the unanswered questions were why an earlier FBI investigation into the gunman was closed two years before the shooting and whether the slaughter at the popular gay club was an act of politically driven rage or triggered by personal demons - or even a mix of both.