SOUTH PORTLAND – A police officer was released from the hospital but a man accused of firing at officers as they attempted to serve an arrest warrant remained in critical condition on Thursday, authorities said.

Officer Steven Connors of the South Portland Police Department and assailant Terrel Dubois of Portland were hit multiple times in a brief gunbattle in which witnesses said as many as 20 shots were fired Wednesday night.

Connors, who was shot four times, underwent emergency surgery before being released Thursday from Maine Medical Center in Portland.

Dubois, 22, remained in critical condition at the same hospital, where he was under police guard. He was reportedly hit several times.

Three Portland officers joined Connors in going to the apartment building to arrest Dubois, who was wanted on charges of kidnapping, criminal threatening and terrorizing, all related to a domestic violence incident, as well as for violating bail conditions, South Portland Police Chief Edward Googins said Thursday.

When the four went into the building to make the arrest, Dubois confronted them and the two sides exchanged gunfire, Googins said.

Connors was shot in the right side of his head, his right shoulder, his left torso and his left hand, Googins said.

After the shooting, police obtained a search warrant and recovered a handgun that they believe Dubois used in the shooting.

Based on what detectives saw in the apartment, they obtained a second warrant and recovered additional evidence that’s expected to support more charges against Dubois, Googins said. He declined to elaborate.

The Attorney General’s Office was investigating as it does in all incidents in which an officer uses deadly force.