At least 22 people were killed and dozens more were injured in a mass shooting spree in Maine on Wednesday evening, in what is the deadliest attack on US soil in four years.

State police in Lewiston, the state’s second-largest city, confirmed an active shooter had attacked a restaurant and bowling alley.

Multiple reports, citing police sources, said at least 22 people were killed and up to 60 were injured – the worst death toll since the same number were shot in a Walmart store in El Paso in August 2019.

A manhunt involving hundreds of police is currently under way to find the shooter who remains at large.

Police have released a photograph of a dark-haired, bearded suspect carrying what appears to be a semiautomatic rifle, and appealed for information about an “armed and dangerous” 40-year-old man named Robert Card.

According to a police intelligence bulletin, seen by the Associated Press news agency, Mr Card is a trained firearms instructor at a US Army Reserve facility in Maine who was committed to a mental health facility for two weeks earlier this year.

The document also said Mr Card had reported hearing voices and had threatened to carry out a shooting at the military training base in Saco, Maine.