MIRROR concert organisers have apologised after a large video panel fell from the ceiling above the stage on Thursday evening, injuring two dancers, one of them seriously.

Videos circulating on social media appeared to show the massive video screen striking one dancer on the top of his head before toppling over, trapping another dancer.

Police say their Kowloon City crime squad are investigating the incident.

The concert, at the Hong Kong Coliseum, was organised by Music Nation and MakerVille, a member of PCCW Media Group.

MakerVille's CEO, Lo Ting-fai, visited the injured dancers at Queen Elizabeth Hospital in the early hours of Friday.

He said one of them was in intensive care, but was conscious and able to communicate with doctors.

The other dancer was slightly injured, Lo said.

Lo bowed in apology and promised the company would carry out a thorough investigation.

"We're handling the incident seriously. We promise to find out the cause. We're most concerned about the two injured dancers and their families. We will keep in touch with them and offer all necessary assistance," he said.

In a joint statement, the organisers said they would meet contractors and sub-contractors over the matter, as well as government departments, and their investigation would include looking at whether any negligence was involved.

Any misconduct uncovered would be reported to the police, the statement added.

The president of Hong Kong Performing Artistes Guild, Louis Koo, said he was shocked and upset about the incident, which followed earlier safety concerns regarding the concerts.

He appealed to the public to stop sharing videos of what happened.

Koo said a comprehensive review should be carried out on performance safety to prevent similar incidents from happening again.

Libby Cheung from the Hong Kong Theatre Arts Practitioners Union said the concert organisers should offer compensation and provide support to the injured dancers.

She urged the organisers and their contractors to disclose whether the stage installations had complied with relevant safety regulations.