A gunman opened fire on five police officers in the eastern US state of Pennsylvania, killing three and seriously injuring two before he was killed at the scene, a senior police official said.

"I can confirm that there were five law enforcement officers who were shot today, three fatally," State Police Commissioner Christopher Paris told reporters on Wednesday, adding that two officers were taken to the hospital in critical condition.

The officers had gone to an address as part of a domestic violence investigation when they came under fire.

"I can confirm that the shooter is dead," Paris added, stating the suspect had been shot by police.

He said an investigation was underway and that there was no ongoing threat to the public.

'Tragic and devastating'

The shooting happened on Wednesday afternoon in the Township of Codorus in York County, 210 kilometres southwest of Philadelphia.

"There are many details, which at this point we are not prepared to release, given the ongoing nature of the investigation," Paris said.

The two wounded officers were in critical but stable condition, he added.

Pennsylvania Governor Josh Shapiro said, "This is an absolutely tragic and devastating day for York County and for the entire Commonwealth of Pennsylvania."

US Attorney General Pam Bondi said on X that "the FBI and ATFHQ are on the scene supporting local law enforcement," adding: "Violence against law enforcement is a scourge on our society and never acceptable. Pray for the officers involved."