The Twitter account of The Voice star Christina Grimmie was hacked after her death, according to a report on the People website.

Hours after the 22-year-old singer was fatally shot by a man carrying two guns, a hunting knife and two loaded gun magazines, her Twitter account sent out a message saying simply, "The End."

The message was retweeted more than 65,000 times within an hour and sparked anger among fans who described it as "eerie" and "morbid".

Grimmie's representatives told People her account had been hacked.

The tweet has since been deleted.

Grimmie, 22, performed late on Friday with the group Before You Exit at Orlando's Plaza Live Theatre and stayed after to sign autographs and sell merchandise.

The gunman approached her and opened fire without warning, then fatally shot himself, according to police.

Grimmie was rushed to the Orlando Regional Medical Centre, but died of her injuries.

Tributes poured in for Grimmie, a New Jersey native who first gained public attention with moving covers of hit songs in videos viewed by millions on YouTube.

She competed in the sixth season of The Voice in 2014.

Earlier on Saturday, a new video of Grimmie's final performance was released, showing the singer performing Without Him - a track off her self-titled EP, which was released in February.

"We are heartbroken," the NBC talent show said on its Twitter account after the shooting, calling the young singer "a loved member of our family."

"There are no words. We lost a beautiful soul w/ an amazing voice," it said after her death was confirmed.

Adam Levine, the singer whose team she performed with on the programme, posted a picture of himself with her on his Instagram account after the incident when the singer was taken wounded but still alive to the hospital.