But Scott said Wray must resign, saying acknowledging a mistake "isn't going to cut it". "Both the House and Senate need to immediately initiate their own investigations into the FBI's protocols for ensuring tips from the public about potential killers are followed through", he said in a statement. "We see the tragic consequences of those failures", Sessions said in a statement.
"The FBI has failed", said Lewis Mizen, a 17-year-old student at Marjory Stoneman Douglas High School, where the attack took place.
"An apology will never bring these 17 Floridians back to life or comfort the families who are in pain", Scott said.
"This is totally destructive to the "see something, say something" narrative that we hear so often from law enforcement", he said.
Florida governor Rick Scott has demanded that Wray resign as a result of the error. The tipster warned about Cruz's gun ownership and mental instability, and expressed concern about him potentially carrying out a school shooting.
In a statement Friday, the agency said the tip on January 5 "should have been assessed as a potential threat to life".
The FBI has earlier confirmed it is investigating its handling of an apparent online threat the suspect is claimed to have made online previous year.
Investigators in Florida now say police received approximately 20 calls related to Nikolas Cruz over the past few years.
Mr Cruz has been charged with 17 counts of premeditated murder.
The FBI said that information should have been assessed as a potential threat to life and passed on to the Miami field office but that "we have determined these protocols were not followed".
'I just ran': What have students said?
FBI Director Christopher Wray said the agency was still reviewing its missteps on the January tip.
Among the dead: assistant football coach Aaron Feis, slain while shielding students from bullets; Joaquin Oliver, a student known for his unique look and who once dyed his hair bleach-blonde with tiger stripes; Alyssa Alhadeff, an avid soccer player and student; and 35-year-old geography teacher Scott Beigel, who helped students enter a locked classroom, only to be shot himself.
The FBI, which has been a frequent target of criticism from the Trump administration and Republican lawmakers, now faces additional scrutiny after admitting Friday that it botched a tip that could have averted Wednesday's massacre in Parkland, Fla.
The deadly high school shooting in south Florida has led to a number of copycats threatening to attack schools across the nation. No police reports were immediately available for those calls so it was not possible to determine whether Cruz was involved.
Federal Bureau of Investigation director Christopher Wray says the agency, which received an average of 2,101 calls to the tip line each day in 2017, is still reviewing its missteps on the January tip.
While Marjory Stoneman Douglas High School is closed this week, some students and staff returned to campus Friday to pick up their vehicles that were left behind in the chaos.
"I think I am going to kill people" he told group members, before dismissing the comment as a joke, according to CNN.