5 Seconds of Summer's Luke Hemmings engaged to girlfriend Sierra Deaton

5 Seconds of Summer lead vocalist Luke Hemmings is officially engaged to his longtime girlfriend Sierra Deaton.

A source told People that the guitarist asked his girl to marry him in an intimate scene in Maibu, California in February but remained mum until today.

The singer took to Instagram to officially share the news a few hours ago.

“With shaking hands but a full heart I proposed to my best friend earlier this year.

"I love you Thao and I can’t imagine my life without you,” he wrote about his girlfriend.

The post saw the couple being showered with congratulatory messages.

Take a look: