TALLAHASSEE, FLA. ? A furious gun battle erupted inside a federal prison Wednesday when a guard opened fire on FBI agents who had come to arrest him and several others on charges of having sex with female inmates in exchange for money and contraband. Two people were killed and another was wounded.

The dead were the guard and a U.S. Justice Department investigator. A prison employee helping with the arrest was hospitalized.

Six guards in all had been indicted Tuesday on charges they had sex with the women by bribing them with money and contraband in a scheme that went on for two years. The contraband was not specified but could include drugs and alcohol.

When FBI agents and Justice Department investigators arrived at the prison Wednesday to arrest the men, one of the indicted guards shot a federal correctional officer, said FBI spokesman John Girgenti. He said the officers fired back.

Investigators work at the scene of a shootout at the Tallahassee Federal Correctional Institution in Florida. A federal prison guard unexpectedly opened fire Wednesday on agents who came to arrest him and five others accused of bribing female inmates for sex and to keep quiet, officials said. The guard and an agent died in the shootout, and a prison officer was injured.

The guard fired with a personal weapon, wounding a Bureau of Prisons employee who was assisting with the arrest. Agents from the Justice Department’s inspector general’s office returned fire, killing the guard. A Justice Department agent was killed in the exchange. It was not immediately clear who fired that fatal shot.

“These agents were out just trying to do their job, trying to do an arrest in a very controlled situation, and it just didn’t come down exactly as planned,” FBI agent Michael Folmar said.

Federal Bureau of Prisons spokeswoman Carla Wilson said the prison had been locked down.

Officials did not release the gunman’s identity, but lawyer Tim Jansen said the dead guard was Ralph Hill, his client. The slain Justice Department agent was identified as William “Buddy” Sentner, 44, who formerly worked for the Secret Service before joining the inspector general’s office in 2002.

The identity of the survivor was not disclosed, but he was reported in stable condition. Folmar said the man should fully recover.

Folmar declined to discuss details until an FBI team set to begin work today completes an investigation into the shooting.