(BLOOMBERG) - The National Rifle Association sued Florida over legislation that bars people under 21 years old from buying firearms.

The gun lobby group fired back hours after Governor Rick Scott signed the bill into law on Friday (March 9).

Florida has "prohibited an entire class of law-abiding, responsible citizens from fully exercising the right to keep and bear arms - namely, adults who have reached the age of 18 but are not yet 21," according to the complaint filed in federal court in Tallahassee, the state capital.

The measure violates both the US Constitution's Second Amendment, which provides the right to bear arms, and the 14th Amendment, which guarantees all citizens equal protection under the law, the NRA contends.

"We will review the lawsuit," said John Tupps, a spokesman for the governor, a Republican who has supported gun rights.

Aside from raising the age for gun purchases, the new law imposes a three-day waiting period for long guns, criminalises the possession of bump stocks and starts a programme to arm some teachers.

It doesn't ban automatic weapons, which was one of the requests of students and parents after a 19-year-old gunman killed 17 people at a Florida high school three weeks ago.