Isabel Martinez: Mother accused of stabbing her four young children and their father to death gives thumbs up

The 33-year-old is thought to have alerted police about the killings

Isabel Martinez gestures towards news cameras during her first court appearance Lawrenceville (AP)

A mother accused of stabbing her four young children and their father to death, gave a thumbs up to photographers ahead of her first court hearing.

Isabel Martinez is charged with five counts of malice murder, murder and six counts of aggravated assault after the attack in Atlanta, Georgia.

Gwinnett County police detained Martinez - who is believed to have also called them to alert them about the killings - after bodies were found inside a home in the suburb of Loganville.

A fifth child, a nine-year-old girl, survived and was hospitalised with injuries described as serious, police said.

Police confirmed that the call came from an adult woman who was inside the home, believed to be the suspect.

Investigators said the caller was speaking Spanish, which initially made it difficult for operators to communicate with her.

The county sheriff's office said Martinez is also being held for US Immigration and Customs Enforcement but didn't provide further details.

Early indications are that a knife was used to attack the five, though a medical examiner will make the final determination about the cause of death, police said.

The four children killed have been identified as Isabela Martinez, 10; Dacota Romero, 7; Dillan Romero, 4; and Axel Romero, 2. Their slain father was Martin Romero, 33.

Psychologists and others who study cases of mothers accused of killing their children say it's not as uncommon as people might believe.

But media coverage often focuses on dramatic cases, such as Andrea Yates who was found not guilty by reason of insanity for the 2001 drowning deaths of her five children.

Other cases get less attention, as when a woman hides or leaves a newborn or in children's deaths blamed on neglect, said Cheryl Meyer, a professor of psychology at Wright State University in Ohio.

Police initially said in a statement that a woman inside the home called police at 4:47 am on Thursday to report a stabbing and officers answering the call found the five bodies inside.

Neighbours in the small, largely Hispanic neighbourhood said they had no clue anything was amiss in the home until police mobbed the scene Thursday morning. The neighbours said the Spanish-speaking family had moved to the community recently, and their children seemed happy playing with other neighbourhood kids.

Victoria Nievs said the children's mother had recently suffered the death of her father.

Jim Hollandsworth is spokesman at the Path Project, a nonprofit organisation that runs an after-school program that the family's children participated in. He said the family had been in the community for a few months. While the children spoke English as a second language, he said, they were fluent.

“It's awful. It's devastating. Everyone is in complete shock,” he said. “The kids were engaged in what we're doing. They were happy. They were fantastic kids with a bright future.”

AP