Authorities are searching for a white supremacist Idaho prison inmate and an accomplice who fled after the accomplice shot and wounded corrections officers as they were transporting the inmate from a Boise hospital, according to police.

Police said Nicholas Umphenour is suspected of shooting two corrections officers during Wednesday's ambush in the ambulance bay at Saint Alphonsus Regional Medical Center. A warrant with a $2 million bond has been issued for his arrest on two charges of aggravated battery against law enforcement and one charge of aiding and abetting an escape, police said.

He and inmate Skylar Meade drove off early Wednesday after the shooting in a gray 2020 Honda Civic with Idaho plates. It's not known where they are or where they are headed, police said Wednesday evening.

Three corrections officers were shot and wounded during the attack — two allegedly by Umphenour and one by responding police.

Officials described Meade, 31, as a white supremacist gang member. Meade was sentenced to 20 years in 2017 for shooting at a sheriff's sergeant during a high-speed chase.

The attack occurred at 2:15 a.m. as Idaho Department of Correction officers prepared to bring Meade back to prison. Department Director Josh Tewalt said during a news conference Wednesday afternoon that Meade was taken to the hospital at 9:35 p.m. Tuesday after he engaged in "self-injurious behavior" and medical staff determined he needed emergency care.

One officer shot by the suspect was in critical but stable condition, police said, while the second wounded officer had serious but non-life-threatening injuries. The third injured corrections officer also sustained non-life-threatening injuries when a responding officer — incorrectly believing the shooter was still in the emergency room and seeing an armed person near the entrance — opened fire.

"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 in a written statement.

Umphenour, 5-foot-11 and 160 pounds, has brown hair and hazel eyes, police said. Detectives have confirmed that he is an associate of Meade, police said. Attempts by The Associated Press to reach Umphenour through social media were unsuccessful.

Meade, 5-foot-6 and 150 pounds, has face tattoos with the numbers 1 and 11 — for A and K, the first and 11th letters of the alphabet, representing the Aryan Knights gang he affiliated with, Tewalt said. Photos released by police also showed an A and K tattooed on his abdomen.

The Aryan Knights formed in the mid-1990s in the Idaho prison system to organize criminal activity for a select group of white people in custody, according to the U.S. attorney's office in the district of Idaho.

Meade had been held in a type of solitary confinement called administrative segregation at Idaho Maximum Security Institution in Kuna, about 12 miles south of Boise, because officials deemed him a severe security risk, Tewalt said.

Tewalt said earlier in the day that Meade had been escorted in the ambulance and at the hospital by two uniformed, unarmed officers wearing ballistic vests, tailed by armed staff. Later in the day Correction Department spokesperson Sanda Kuzeta-Cerimagic said in an email that officials had confirmed that one officer had been in the ambulance with Meade and two officers were in an escort vehicle.

"To the best of our knowledge, Meade was in restraints while being escorted in and out of the hospital," Kuzeta-Cerimagic said. She didn't specify whether the restraints were handcuffs, shackles or another type of restraint but said transport procedures are dependent on the custody level of the person being transported.

Authorities also did not say if other security measures were in place when Meade was leaving the hospital.

The attack came amid a wave of gun violence at hospitals and medical centers, 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 center 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 Wednesday morning in a statement.

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.

Ramirez declined to comment when asked about Meade, deferring to the police department.