Tristan Thompson is grieving a major loss.

TMZ reports the NBA star’s mother, Andrea Thompson, died Thursday in her Toronto home after suffering a heart attack. Sources say the woman was immediately rushed to the hospital, where doctors attempted to resuscitate her without success. Insiders said the the death was unexpected.

Thompson reportedly left Los Angeles on Thursday and landed in Canada alongside Khloé Kardashian, with whom he shares two children. According to TMZ, Khloé maintained a close relationship with Andrea Thompson, even after her split from Tristan.

Sources tell Entertainment Tonight that Kris Jenner and Kim Kardashian will attend Andrea’s private funeral.

“Khloé was very close to Tristan’s mother,” an Insider told the outlet, “and as with any partner, friend, etcetera, the family will be first to support them, especially in this very difficult time.”

Tristan has not publicly commented on his mother’s death.

“I talk to my mom every day – ask how the kids are doing, ask how she’s doing, too,” Tristan said in a 2016 NBA interview. “Everyone knows that my mom, she’s very dedicated in taking care of her sons – especially Amari. But at the same time, you need to make sure that she’s ok.”

He continued: “It’s asking a lot for one parent to do, so I always try to make sure that she’s doing well, too. Whether she’s getting a massage or just get out of the house and have a babysitter watch for a couple hours, that’s crucial.”