A GUNMAN STAGED a brazen attack to free a prison inmate from an Idaho hospital overnight, shooting and seriously wounding two corrections officers, US police said.

A third prison officer was also shot and wounded when arriving police mistook them for the suspect and opened fire.

One officer is in a critical but stable condition, another has serious but non-life-threatening injuries and the third was not seriously injured when mistakenly shot by an arriving Boise police officer, a spokesperson said.

The gunfire happened after prison officers took inmate Skylar Meade to St Alphonse hospital for medical treatment at 2.15am. As they were preparing to return to the jail, an unknown suspect began shooting at officers, striking two of them.

Boise police responded to the incident and one officer fired at an armed person near the entrance, who was later determined to be a corrections officer.

Meade, who was sentenced to 20 years in prison in 2017 for shooting at a sheriff’s sergeant during a high-speed chase, and the gunman fled in a grey four-door sedan, possibly a Honda Civic, with Idaho plates.

“This brazen, violent, and apparently coordinated attack on Idaho Department of Corrections personnel, to facilitate an escape of a dangerous inmate, was carried out right in front of the Emergency Department, where people come for medical help, often in the direst circumstances,” Boise police chief Ron Winegar said.

The attack is part of a wave of gun violence at hospitals and medical centres, which have struggled to adapt to the threats.

A Saint Alphonsus spokesperson said the shooting happened in the ambulance bay by its emergency department.

“All patients and staff are safe, the medical centre campus is safe and secure, and has resumed normal operations. The Emergency Department itself is currently under temporary lockdown while the Boise Police Department completes the investigation,” Leticia Ramirez said.

She said as an added precaution “we have increased security on campus, all entrances to the hospital will be closed” and monitored by hospital security until further notice.