The FBI has said it did not properly follow up on a warning that Florida school shooting suspect Nikolas Cruz might carry out an attack.

Last month, a person close to the 19-year-old contacted the law enforcement agency to warn of “the potential of him conducting a school shooting”.

But protocols were not followed and the tipline did not pass along the complaint, the FBI said.

It was not the first potential warning to the FBI regarding Mr Cruz.

He has confessed to carrying out the attack at Marjory Stoneman Douglas High School in Parkland and has been charged with 17 counts of murder.

It was the deadliest US school shooting since 2012.

Florida Governor Rick Scott said in furious statement that the director of the FBI must resign because of the law enforcement agency’s “failure to take action against this killer is unacceptable”.

“The families will spend a lifetime wondering how this could happen, and an apology will never give them answers they desperately need.”

The Republican governor said Americans must have confidence in the FBI to act on “see something, say something” tips.

A group of Florida lawmakers who travelled from the state capitol to visit the school on Thursday agreed to tear down and replace Building 12, where the massacre occurred.

“It will still be very difficult for students to return,” Republican Senator Bill Galvano told the Miami Herald newspaper.

“But that particular building should be razed, and the memory of the perpetrator erased and a memorial honoring the victims and their families be put in its place.”