A nine-year-old in Illinois has been charged with five counts of first-degree murder following a deadly mobile home fire that killed five people, including three children, the youngest of whom was one year old.

The child also was charged on Tuesday with two counts of arson and one count of aggravated arson, a charge that the state’s attorney office said suggests the suspect knew that people were inside the home when it was set ablaze.

“It was a heavy decision”, Woodford County State’s Attorney Greg Minger told the Journal Star. “It’s a tragedy, but at the end of the day it’s charging a very young person with one of the most serious crimes we have.”

The child’s identity has not been disclosed, but on Tuesday, Woodford County Coroner Tim Ruestman referred to the suspect as a “he.”

The blaze started at around 11pm on 4 April at Timberlane Mobile Home Park near Goodfield, a village near Peoria. Firefighters arrived within minutes to find the mobile home engulfed in flames. Mr Ruestman had ruled that the fire was intentionally set.

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Kathryn Murray, 69, Jason Wall, 34, and two-year-olds Rose Alwood and Daemeon Wall and one-year-old Ariel Wall died due to smoke inhalation, according to post mortems.

Two people survived the fire, including Mr Wall’s fiancee Katrina Alwood and her young son.

Ms Alwood and Mr Wall were the parents of Ariel and Daemeon Wall. Rose Alwood was a niece, and Ms Murray was Ms Alwood’s grandmother.

The state’s attorney’s office did not disclose whether the nine-year-old suspect knew the victims.

Mr Minger said an arrest warrant will not be issued for the child, and he’s not certain whether there is a minimum age threshold for imprisoning a minor. Instead, he will be appointed an attorney and brought before a judge for a bench trial. No jury will be present, and jail time is not possible; if found guilty, the child could face a minimum of five years of probation, along with counselling and therapy, according to Mr Minger.

He told the Journal Star that “probation, given the age, is about the only outcome that could happen here.”

The charges are among several recent high profile cases in the US involving children under 10 years old, according to data collected by ABC News.

More than 30,000 children aged under 10 were arrested in the US within the last six years, according to annual crime statistics from the Federal Bureau of Investigation.

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Thirty-four states don’t have a minimum age for delinquency, and 24 states have no minimum age requirement to send juvenile cases to criminal court.