Washington (CNN) White House press secretary Sarah Sanders tried to finesse a weekend tweet from President Donald Trump blaming the FBI's Russia investigation for missing a tip about the Florida shooting, saying the agency should not focus on a "hoax in terms of investigating the Trump campaign."

"Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable. They are spending too much time trying to prove Russian collusion with the Trump campaign - there is no collusion. Get back to the basics and make us all proud!" Trump tweeted.

Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable. They are spending too much time trying to prove Russian collusion with the Trump campaign - there is no collusion. Get back to the basics and make us all proud! — Donald J. Trump (@realDonaldTrump) February 18, 2018

Sanders, speaking to reporters Tuesday in her first briefing since the shooting, said the President wasn't saying "necessarily" that the Russia investigation was responsible for the FBI missing the signs on the Florida shooter.

"I think he was speaking not necessarily that is the cause. I think we all have to be aware that the cause of this was a deranged individual that made a decision to take the lives of 17 other people," Sanders said. "That is the responsibility of the shooter, certainly not the responsibility of anybody else."

She added: "I think he is making the point that we would like our FBI agencies to not be focused on something that is clearly a hoax in terms of investigating the Trump campaign."