Presumptive Republican presidential nominee Donald Trump responded on Monday to the deadliest mass shooting in American history, which rocked Orlando, Florida on Sunday, leaving 49 victims dead and 53 wounded.

Describing the immigration of Muslim refugees into the US as the “all-time Trojan horse”, Trump blasted local Muslim leaders for not exposing “bad apples” with inclinations towards radicalism.

“They don’t report these people,” said Trump during an interview on Fox News. “The people know who the bad apples are, where the bad seeds are. And they don’t report them.”

“You’ll find out shortly, you’ll find out that many people knew that he was bad. Many people knew he had some kind of an idea for an attack. It happens all the time. Almost all the time. We need much better intelligence.”

The perpetrator, Omar Mateen, was born in the US to Afghan refugees. Mateen declared allegiance with ISIS and has been under investigation by the FBI since 2013. Mateen was killed during a shootout with police during his attack on an Orlando nightclub.

Trump also condemned President Barack Obama’s response to the attack, noting that he had failed to refer to the incident as “radical Islamic terror”. The GOP nominee demanded the president resign, lambasting the continued immigration of refugees from countries like Syria and Afghanistan, as well as the president’s renewed call for comprehensive legislation limiting gun ownership.

“Calling on another gun ban – I mean, this man has no clue. First of all, the shooter was licensed. So he went through all the procedures, he was fully licensed to have a gun, so he would have passed the test the president would have thrown up there.”

“This is a mentality… and you have thousands of shooters like this with this mentality out there in this country. And we’re bringing thousands and thousands of them back into this country and into the country every year. We’re allowing them into the country.”

Trump also blasted likely Democratic nominee Hillary Clinton, calling her “weak” and suggesting she was “like a maniac”, citing claims by a former Secret Service agent assigned to the former First Lady.

“She’s a weak person. She’s weak on so many different levels. I just see where the Secret Service agency said she should never be president. He called her almost like a maniac.”

“She is not the right person, especially in these times.”