What was supposed to be a night of pop music and excitement ended in tragedy Monday when a bomb tore through the foyer of an arena in Manchester, England, just as a concert was ending.

For Medford’s Bianca Landrau, one of the concert’s opening acts, the devastation left her praying for the safety of concertgoers.

A rapper and performer who graduated from Medford High in 2008, Landrau is best known by her stage name, Bia.

She opened for pop star Ariana Grande at the Manchester concert where 22 people were killed in a suicide bombing and dozens more were injured.

Landrau was not available for interviews on Tuesday, but in the aftermath of the bombing, she posted a statement to Twitter that read in part: “My heart is heavy today as i extend my prayers to the children and families affected by last nights horrible tragedy in Manchester. . . . We ask each one of you to join us in keeping all who are suffering in your thoughts and prayers.’’

The singer’s uncle, Anthony Tamasi, told the Globe he’d spoken to his niece by phone Tuesday afternoon.

He said Landrau was grieving for the victims of the blast and their families.

“Bianca is OK but very upset,’’ Tamasi said in an interview at his home in Medford. “She’s still in England.

“Her heart is with the people who died,’’ he said. “Nobody ever expected this. . . . My heart goes out to the people in Manchester.’’

Landrau is scheduled to open for Grande’s “Dangerous Woman’’ tour again in London Thursday and Friday, according to her website.

There are conflicting reports as to whether those shows will go on as scheduled or if the tour has been suspended.

“Right now everything is up in the air,’’ Tamasi said.

In Medford, people were thinking of Landrau and of the horrible tragedy that has unfolded in England.

“My understanding of her is that she was a really active young lady . . . who wanted to help and support groups that needed help,’’ Medford High headmaster John Perella said in a phone interview.

Although Perella said he didn’t know the singer personally, he works with teachers who knew Landrau as a student.

“She even had that kind of focus in high school,’’ he said.

Tamasi said Landrau was born and raised in Medford and has always been interested in music, dance, and performance.

He recalled how, even as a young child, she would sing while doing her homework.

In 2014, six years after graduating from high school, Landrau could be seen on Oxygen’s “Sisterhood of Hip Hop,’’ a series about female artists trying to build their careers.

Landrau got her first big break when she was discovered by rapper Fam-Lay, who introduced her to Grammy-winning singer and producer Pharrell Williams.

The first day she met Williams, he challenged her to write a 16-bar verse to a beat.

“He threw a song on and said, ‘Write a 16 [bar verse] to this. If it’s good, I’ll keep you on, and if it’s bad, I’m gonna take you off,’ ’’ Landrau said in an interview on Oxygen.com.

“That was the first day I met him. It was do or die. It took me 15, 20 minutes. I went in the studio, recorded it and came out, and it was history.’’

Vibe magazine described her as Pharrell’s protege in 2016.

After Landrau posted her statement on Twitter and Instagram accounts Tuesday, her followers responded with words of sympathy and support.

One fan tweeted: “stay together and stay strong. this tour has brought nothing but light and I’m so sorry this has happened. We love you.’’

Another fan posted on Twitter: “stay strong’’ with a heart symbol, while another wrote: “Praying for those that lost their lives / got injured and their families. We will all stand together. We love you.’’