Investigators are collecting data from at least two cellphones used by Omar Mateen, the gunman who killed 49 people at a gay nightclub Sunday, as well as other electronic media and email accounts, a U.S. law enforcement official said Tuesday.

So far, the official said, investigators have not encountered any data that has been encrypted, a major stumbling block in the FBI’s investigation of an iPhone used by the couple who killed 14 people at a holiday party in San Bernardino on Dec. 2.

The lack of encryption is expected to speed the widening investigation into why Mateen, a 29-year-old private security guard, opened fire with a semi-automatic rifle in the Pulse nightclub. He was killed later in a shootout with police.

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Around 40 victims of the shooting remain in local hospitals, with many undergoing repeated surgeries.

Six remain in critical condition, Dr. Michael Cheatham, a trauma surgeon at Orlando Regional Medical Center, said at a news conference.

He said he would be surprised if the death toll does not rise.

“This is the largest disaster that we probably could have imagined,” Cheatham said.

President Barack Obama met with his national security team at the White House for a briefing on the investigation. He will visit Orlando on Thursday.

FBI officials believe Mateen had visited Pulse and frequented other gay clubs in the past and had used a dating app on his phone to meet other men.

That has added an unexpected wrinkle to the case, since Mateen called 911 during his rampage to pledge loyalty to the head of the Islamic State, a terrorist group that executes homosexuals by throwing them off tall buildings.

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Investigators are also seeking to determine if Mateen scouted other possible targets.

The FBI has obtained evidence that Mateen visited Disney World in Orlando in April, perhaps to familiarize himself with the park’s layout, a U.S. law enforcement official said.

The official said it was clear that Mateen’s visit involved more than tourism but cautioned that agents may never learn fully if he was casing Disney properties for a potential attack.

He also is believed to have visited other gay venues he may have been considering as targets, the official said.

A top U.S. law enforcement official said the investigation has not found evidence that anyone helped Mateen plot the attack and no charges against other individuals are imminent.

The investigation has also extended to Afghanistan, where his parents were from, and to Saudi Arabia.

Mateen traveled to Mecca in Saudi Arabia for 10 days in March 2011 and for eight days in March 2012 to take part in the annual religious pilgrimage made by Muslims, a U.S. law enforcement official said.

During 2013, when the FBI launched a 10-month investigation of Mateen for possible terrorist ties, U.S. authorities asked Saudi intelligence officials about the two trips, officials said.

The Saudis had no evidence suggesting Mateen had held suspicious meetings while in the kingdom, or engaged in any other behavior that raised any alarms.

The day after a massive candlelight vigil in downtown Orlando, city officials were able to release the names of all 49 people killed — mostly Latinos in their 20s and 30s.

Doctors said the volume of patients with severe gunshot wounds surpassed anything they had ever handled. Initially, it was thought many patients would succumb to those wounds, but most have stabilized, doctors said.

Many of the victims were originally from Puerto Rico, with four of the dead from Mexico.

Mateen’s ex-wife, Sitora Yusufiy, was asked in a CNN interview if he might have been gay, and she said she did not know. But, she said, he spoke as if he hated gays.

Kevin West, a regular at Pulse, told the Los Angeles Times that Mateen messaged him on and off for a year before the shooting, using the gay chat and dating app Jack’d.

At least four regular customers of Pulse told the Orlando Sentinel that they believed they had seen Mateen there before.

A former classmate recalled that Mateen seemed like a “regular dude” until the Sept. 11 attacks in 2001.

“At first, I was surprised … like, damn bro, I rode the bus with that kid,” said Robert Zirkle, 29, who attended Martin County High School in Stuart, Fla. “But then I got remembering and thinking … he was crazy then, but nobody connected the dots.

“He started acting crazy, joking around the fact that 9/11 happened, making plane noises on the school bus and pretending he was slamming into the building,” said Zirkle, who now lives in Johnston City, Tenn., where he is a manager at a McDonald’s.

Mateen was investigated by the FBI in 2013 and 2014 after he told co-workers that he planned to kill people and wanted to die as a martyr in a police raid. He was removed from the FBI’s terrorist watch list in 2014 after investigators concluded he was full of bluster and not a real threat.

He was questioned again by the FBI after Moner Mohammad Abusalha joined the Nusra Front, an al-Qaida affiliate in Syria and killed more than a dozen people in a truck bomb suicide attack in Syria in 2014.

The FBI concluded that Mateen and Moner attended the same mosque but knew each other only casually.

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