Buddy Dyer, the Orlando mayor, said Mateen drove around several locations in the Orlando area Saturday evening, before he picked Pulse.

“What I know concretely is that he was driving around that evening and visited several locations,” Dyer said. He did not elaborate.

And, Dyer said, Mateen had threatened to strap explosives onto the hostages, hastening the decision to send a SWAT team to the location to end the standoff.

“We had independent verification of that,” Dyer said. “We had a lot of information from the inside and they independently were saying yes, the bomber is about to put on an explosive vest.”

It’s unclear, however, whether Mateen actually possessed explosives at the time.

7:13 p.m. ET

What did Omar Mateen’s wife know?

NBC and others are reporting Omar Mateen’s wife, Noor Zahi Salman, might have been aware of the plot to attack Pulse. She told federal agents she tried to talk him out of Sunday’s attack, NBC reported.

Here’s more:

Omar Mateen's wife, Noor Zahi Salman, told the FBI she was with him when he bought ammunition and a holster, several officials familiar with the case said. She told the FBI that she once drove him to the gay nightclub, Pulse, because he wanted to scope it out. … Authorities are considering filing criminal charges against Noor for failing to tell them what she knew before the brutal attack, law enforcement officials say, but no decision has been made.

News reports say she is cooperating with investigators.

12:50 p.m.

Obama addresses terrorism

The president, speaking at the White House, reiterated some of what we already know about Omar Mateen.

“We currently do not have any information to indicate that a foreign terrorist group directed the attack in Orlando,” he said. “It is increasingly clear, however, that the killer took in extremist information and propaganda over the internet. He appears to have been an angry, disturbed, unstable young man who became radicalized.”

Obama said lone-wolf actors like Mateen are hard to detect, but “we are doing everything in our power to stop these kinds of attacks.

“We work to succeed 100 percent of the time,” Obama said. “The attacker, as we saw in Orlando, only has to succeed once.”

Obama also took the opportunity to rail against the proposal by Donald Trump, the presumptive Republican presidential nominee, to temporarily ban Muslim immigration to the U.S.

“The Orlando killer, one of the San Bernardino killers, the Fort Hood killer, they were all U.S. citizens,” Obama said. “Are we going to start treating all Muslim Americans differently? Are we going to start subjecting them to special surveillance? Are we going to start discriminating them because of their faith? We’ve heard these suggestions during the course of this campaign. Do republican officials actually agree with this? Because that’s not the america we want.”