Jordin Sparks mourns deaths of loved ones, including step-sister

Pop star Jordin Sparks mourned the deaths of four loved ones who each died in the past week.

The singer shared her heartbreak in an Instagram tribute after losing her teenage step-sister Bryanna Jackson-Frias, her cousin "Q" and her friends Rasual Butler and Leah LaBelle.

"My heart is just so heavy & broken. I'm in shock, numb and feel everything all at the same time," Sparks wrote in the post. "Leah & Rasual (one of my closest friends and her amazing other half who also was a great friend), Bryanna (my step sister) and Q (my little cousin), you were such bright lights in this crazy world."

She continued: "You made everyone better just by knowing them. And your smiles made anyone's day better. The world is less sparkly without you in it. Rest In Peace and Power. I love you forever."

See photos of Leah LaBelle:

Jackson-Frias, 16, died Tuesday after a lengthy battle with sickle cell anemia, People magazine reported. Sparks had asked her fans earlier that day to pray for Jackson-Frias, noting in a post to her Instagram story that her step-sister was in the intensive care unit "suffering from complications" stemming from the disease.

The teenage girl's mother, Jodi Jackson, shared the tragic news that her daughter had died in a Facebook post on Wednesday.

"Bry went peacefully to Heaven," she captioned a photo of Jackson-Frias. "I can't help to think that she's smiling just like this. Thank you all for your prayers."

Butler, a former NBA player, and his wife LaBelle, a singer, were killed in a single-car accident early Wednesday morning. Butler was driving at a high speed when his vehicle collided with the curb before hitting three parking meters and a concrete wall and flipping over twice, police said.

Butler was 38, and LaBelle was 31.

Sparks did not provide the identity of her cousin Q, nor did she reveal a cause of death. A rep for the singer did not immediately respond a request for comment.