FBI Director Christopher Wray said the bureau was "still investigating the facts".
David M. Shapiro, a former FBI special agent who now teaches at John Jay College of Criminal Justice, said that the tip about Cruz is what the intelligence community calls an "initial lead" and could result in a "preliminary inquiry", to deduce whether there is a credible threat, in violation of federal law.
The tipster, who called an FBI hot line on January 5, told the bureau that Cruz had a "desire to kill people, erratic behavior, and disturbing social media posts, as well as the potential of him conducting a school shooting", the FBI said.
Parkland Vice Mayor Stacy Kagan said she was organizing a trip next week to Tallahassee to urge lawmakers to act on gun reforms.
Cruz, who was expelled from Marjory Stoneman Douglas High School last year, went on a rampage at the school on Wednesday using an AR-15-style semi-automatic rifle that he legally purchased a year ago.
That information should have been forwarded to the FBI's Miami field office for further investigation, but "we have determined that these protocols were not followed", the agency said.
The review will be conducted by Deputy Attorney General Rod Rosenstein.
"People keep asking us, what about the Stoneman Douglas shooting is going to be different, because this has happened before and change hasn't come?" said Kasky.
"We see the tragic consequences of those failures", Sessions said in a statement.
A2's shares hit record on 1H results, Fonterra deal
It is dual-listed on both the NZX and ASX and has almost 10 per cent of the fresh milk market by value in Australia. He said it would also give Fonterra an exclusive licence to produce and sell A2 branded liquid milk in New Zealand.
The earliest known tip to the bureau came from a bail bondsman in MS who told the FBI in September about a worrying comment left on his YouTube channel from a "nikolas cruz" saying "Im going to be a professional school shooter". He added, "No other information was included with that comment which would indicate a time location or the true identity of the person who made the comment". North Fort Myers High School in Lee County was the recipient of the largest grant from the charity arm of the powerful gun-rights lobby organization, amounting to some $37,000.
The grief and anger of Meadow's father Andrew Pollack boiled over at her funeral as he yelled: "You killed my kid!" "Please pray that this horrific tragedy never happens to another family".
Since the shooting, Trump has faced teary pleas from some relatives of the dead including Lori Alhadeff, whose 14-year-old daughter Alyssa was killed.
Is that how much these people are worth to you, Trump? "Him coming here is absolutely absurd, and he's a hypocrite", Democrat Mark Bogen told CNN, speaking about Trump's announcement that he would travel the stricken city of Parkland on Friday. "And then we can get back to our normal everyday lives, you know".
But Trump risked being greeted with angry demands for action on laws that allowed Cruz to amass an arsenal.
The couple who took in the Florida school shooting suspect after his mother died says he told them he was sorry after the shooting.
President Donald Trump has kept largely silent about the Florida school shooting victims and the escalating gun control debate.
The president focused instead on offering sympathy to the families of the victims and the need to provide better mental health care.
Since the shooting, many survivors have called for the beginning of conversations on politics and gun control.