Frankie, 34, and his younger sister, 23, are close, though he was not among the family members to greet Ariana in Florida when she returned to the U.S. on Tuesday.
“Mac waited for Ariana at the bottom of the [private jet] stairs,” a source told PEOPLE. “She looked distraught and like she had been crying. They hugged for a while before they headed to a waiting car. Ariana’s mom Joan was with her.”
Another Grande source told PEOPLE that the singer was beyond heartbroken about the terror attack, which killed 22 and injured 59 more.
“It’s so, so sad. She loves her fans and is absolutely crushed and devastated as you can imagine. She can’t believe this happened. She just wants to be with her family and loved ones right now,” the insider said.
Around 10:33 p.m. local time on Monday, an explosive went off near the ticket office outside the Manchester Arena, Greater Manchester Police Chief Constable Ian Hopkins said during a press conference on Tuesday. Ariana’s Dangerous Woman tour performance had just concluded.
Authorities believe 22-year-old Salman Abedi detonated the device in a suicide bombing.
RELATED VIDEO: Police Chief Constable Confirms 22 Dead & 59 Injured at Ariana Grande Manchester Arena Suicide Bombing
On Tuesday night, British Prime Minister Theresa May raised the country’s terror threat level from “severe” to “critical,” and expressed concerns over another potential attack.
Grande’s tour is scheduled to continue in London on Thursday, but it remains unclear if she will postpone the performance.
On Monday night, she issued her first, and so far, only, statement about the incident, writing on Twitter, “Broken. From the bottom of my heart, I am so so sorry. I don’t have words.”