President Donald Trump said on Saturday that the FBI had neglected warning signs about the February 14 Florida shooting.
Mr Trump took to social media to criticise the agency, after it disclosed that it had failed to follow up on warnings about the 19-year-old gunman, who is charged with killing 17 people and wounding a dozen others on Wednesday.
“Very sad that the FBI missed all of the many signals sent out by the Florida school shooter. This is not acceptable,” Mr Trump tweeted on Saturday night, adding that the agency had been spending "trying to prove Russian collusion with the Trump campaign".
According to a statement issued by the FBI on Friday, a person close to the shooter contacted the agency's tip line in January "to report concerns about him" and provide information about Mr Cruz's "gun ownership, desire to kill people, erratic behaviour, and disturbing social media posts, as well as the potential of him conducting a school shooting”.
Florida governor Rick Scott called for the resignation of FBI director Christopher Wray, claiming that the FBI’s failure was “unacceptable”.
"Seventeen innocent people are dead and acknowledging a mistake isn't going to cut it," Mr Scott said. "The FBI director needs to resign."
Attorney General Jeff Sessions said he had initiated a justice department review of how the FBI acted. "It is now clear that the warning signs were there and tips to the FBI were missed. We see the tragic consequences of those failures," he said.
The revelation comes as Mr Trump and congressional Republicans have criticised the FBI for its conduct of investigations into his campaign and into Hillary Clinton’s use of private email while she was secretary of state.
President Trump also suggested on the day after the shooting that the community in Parkland Florida should have reported suspicions about Mr Cruz to authorities.
Broward County Sheriff Scott Israel said at on Friday that his office had received more than 20 calls about Mr Cruz in the past few years, according to the Associated Press.
Florida Senator Marco Rubio, a Republican, and Representative Ted Deutch, a Democrat who represents the area, said Congress must conduct its own investigation. “Our system utterly failed the families of 17 innocent souls,” Mr Rubio said.
The FBI said the information from the caller should have been “assessed as a potential threat to life” and should have been forwarded to its Miami field office, “where appropriate investigative steps would have been taken”.
“We have determined that these protocols were not followed for the information,” the bureau said. “The information was not provided to the Miami field office, and no further investigation was conducted at that time.”
In a letter to Mr Wray released on Friday night, Bob Goodlatte, the chairman of the House Judiciary Committee, and Trey Gowdy, the chairman of the House Oversight and Government Reform Committee, asked the bureau to “brief the committees on the tip, protocols, and FBI’s actions before and after the incident as soon as possible, but no later than March 2, 2018”.
Authorities said that Mr Cruz attacked the school pupils with a semiautomatic AR-15-style rifle that he bought legally. It was the same type of firearm that has been used in many mass shootings, including in Las Vegas last year, Orlando in 2016 and at Sandy Hook Elementary School in Newtown, Connecticut, in 2012. The Parkland massacre was the deadliest school shooting since 20 children and six adults were killed in the rampage at Sandy Hook.
Cruz has admitted to the shooting, according to an arrest affidavit reported by The New York Times and others.
Mr Wray said he was “committed to getting to the bottom of what happened in this particular matter, as well as reviewing our processes for responding to information that we receive from the public”.
On Friday, President Trump met medical staff and some victims at Broward Health North Hospital and also stopped at the Broward sheriff's office. He made the visits on the way to his Mar-a-Lago resort in Palm Beach. He later tweeted pictures from the hospital visit.