Kate Middleton has officially returned to husband Prince William's side for royal duties after successfully completing her chemotherapy treatment.

On Thursday, the Prince and Princess of Wales met with the families of the young victims who were killed in a mass stabbing at a Taylor Swift-themed dance class in July. While William was expected to attend, Middleton arrived to Southport unannounced. 

Three children were killed on July 29. Ten others were injured, and a 17-year-old boy has since been charged with the murder of the three young girls who were killed.

Kate Middleton, Prince William

Kate Middleton joined Prince William, unannounced, for a visit to Southport to meet with the families of the young victims who were killed during the July 29 mass stabbing. (Getty Images)

Middleton and William issued a statement of sympathy at the time of the attack.

KATE MIDDLETON HELPS TEEN WITH CANCER FULFILL 'BUCKET LIST' DREAM AFTER FINISHING OWN CHEMOTHERAPY TREATMENT

"As parents, we cannot begin to imagine what the families, friends and loved ones of those killed and injured in Southport today are going through," the statement, shared on X, began. 

"We send our love, thoughts and prayers to all those involved in this horrid and heinous attack. Thank you also to the emergency responders who, despite being met with the most horrific scenes, demonstrated compassion and professionalism when your community needed you most. W & C," the royals concluded.

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Not only did Kate and William meet with the families, they also met with fire, ambulance, air ambulance and police services at the Southport Community Centre.

Prince William, Kate Middleton speaking to first responders

Prince William and Kate Middleton spoke with members of the Emergency Services during a visit to Southport Community Centre on Thursday. (Danny Lawson - WPA Pool/Getty Images)

Taylor Swift wearing blue bodysuit and jacket on stage

Three young girls were killed at a Taylor Swift-themed dance class in Southport, England, on July 29. (TAS2024/Getty Images)

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They talked to the first responders about how responding to the horrific incident affected their mental health and well-being. Oct. 10 is World Mental Health Day, and the royals also spoke with mental health professionals who have been aiding the people involved in the tragedy, People magazine reported.

Prince William and Kate Middleton in Southport

The royal couple spoke with the families and first responders on World Mental Health Day. (Danny Lawson - WPA Pool/Getty Images)

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This marks Middleton's first public royal engagement since she announced on Sept. 9 that she completed her chemotherapy treatment. She revealed in March that she was undergoing treatment for her cancer diagnosis.