Cheryl Treadway and her three children were allegedly being held in their home by her boyfriend Ethan Nickerson, who was armed with a large knife, on Monday afternoon. Nickerson had reportedly taken his girlfriend's phone away from her and only allowed her to use it for a moment after she convinced him to allow her to order a pizza, police say.

Ms Treadway placed her order using a Pizza Hut app she had on her phone but included two messages for staff which raised the alarm.

"Please help, get 911 to me" she wrote in the comments section of her order, adding "911 hostage help" in another part of the order.

Both comments were automatically added to the receipt generated by the app, which was received by the staff at her local Pizza Hut in Avon Park.

Staff at the fast-food restaurant noticed the comments and contacted the local Highland's County Sheriff's Office, who sent police officers to the address immediately.

"Upon arrival at the home, deputies were greeted by [Treadway] carrying a small child in her arms," police said in a statement.

The officers escorted her and the smallest child away from the house and then one of them spoke with the boyfriend through a closed door.

"After about 20 minutes, Lieutenant Ludden was able to talk him into coming out peacefully. The other two children were then removed from the home, unharmed."

Nickerson has been charged with several serious offences, including aggravated assault with a weapon without intent to kill, battery and false imprisonment.

The incident is similar to another case where a woman called 911 about a serious domestic violence incident but pretended she was ordering a pizza so as not to alert her allegedly violent partner to what she was doing.

Australia's National Sexual Assault Domestic Family Violence Counselling Service can be reached on 1800 737 732