TAMPA, Fla. — A Tampa mom accused of killing her "mouthy" children wrote a note before the shootings in which she complained about a three-day waiting period that Florida imposes on gun sales, police say.

Authorities say Julie Powers Schenecker bought a .38-caliber revolver the weekend before the shootings.

Tampa Police spokeswoman Laura McElroy told the St. Petersburg Times that Schenecker wrote in the note that the three-day gap between buying and taking a gun home would "delay the massacre."

The Times said that it was unclear where the gun had been bought, saying police had not said where and no gun store that the paper contacted had admitted they sold the weapon.

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Police have said Schenecker shot her children, 16-year-old Calyx and 13-year-old Beau, for being "mouthy."

She is charged with first-degree murder but her arraignment has not yet been scheduled.

Her husband, Army Col. Parker Schenecker, is in Fort Worth, Texas, for Tuesday's funeral for the children.

The family issued a statement Sunday which described Calyx as "a model student, a published artist, a truly devoted friend and a tenacious athlete," the Times reported.

It also said Beau's "amazing intuition, empathy for others and sense of humor made him stand head and shoulders above the rest."