The 27-year-old 'Locked Out Of Heaven' hitmaker's mother, 55, was rushed to hospital in Honolulu where she is reportedly still in a critical condition, reported Radar online.
Family friend Anita Sojot said that the family are gathering to be at Bernadette's bedside.
"Bernadette is in hospital and the grandkids are all here, I'm looking after them. The family is on its way here right now and we are going to discuss what to do next," she said.
Grammy-winner Mars has been very open about his love for his mother in the past and even wrote a song called 'I Love You Mom' about her, in which he refers to her as a 'superstar' and 'my favourite girl'.
The singer, who is set to kick off on his Moonshine Jungle world tour in Washington DC on June 22, is yet to comment.