The police inquiry into the death of ice hockey player Adam Johnson during a match watched by thousands of fans “will take some time”, the investigating force has said.

The 29-year-old American was playing for Nottingham Panthers at rivals Sheffield Steelers on Saturday when he was reportedly hit in the throat by an opponent’s skate, causing a fatal injury.

About 8,000 fans watched in horror as attempts were made to save Johnson’s life as he lay on the ice, shielded by fellow players.

His team said it was a “freak accident” on Sunday when they confirmed that the popular Minnesota-born player had died.

Since then, South Yorkshire Police have carried out inquiries at the arena, studied footage of the collision and spoken to experts, aided by Sheffield City Council’s health and safety team.

The force said the investigation would be lengthy.

In a statement they said: “Since Saturday, detectives have been carrying out a range of inquiries including reviewing footage, talking to witnesses and seeking the advice and support of highly specialised experts to seek to understand the circumstances surrounding what happened.

“We have also been working closely with the health and safety department at Sheffield City Council, which is supporting our investigation.

“As with all unexpected and sudden deaths, it is standard practice for police to investigate the circumstances fully and feed back our findings to HM coroner.

“Our officers have now left the scene, however due to the complex nature of this tragic and unprecedented incident, it is likely the wider investigation will take some time.

“We continue to encourage the public to avoid speculation, including on social media, while we continue our inquiries and will provide updates when appropriate.

“Our thoughts remain with the loved ones of all those affected.”