By Kristina Sgueglia, CNN

A man accused of shooting two Rochester police officers, killing one, was indicted on 8 counts Wednesday including aggravated murder, second-degree murder, attempted aggravated murder and attempted second-degree murder, according to a grand jury indictment obtained by CNN.

Kelvin J. Vickers Jr is accused of shooting and killing Officer Tony Mazurkiewicz, and of shooting Officer Sino Seng in what officials described as a "cowardly ambush" late last month. The most serious charge, aggravated murder, which he is facing for shooting and killing a police officer, carries a penalty of life in prison without parole, according to the Monroe County District Attorney's Office.

According to the counts for aggravated murder and attempted aggravated murder in the indictment, Vickers knew or reasonably should have known that the men were police officers. The officers were in plain clothes, CNN previously reported.

"The standard is, that the defendant knew or reasonably should have known, and I believe that there is evidence to support that, and hence that's why he's charged as (such) in the indictment," Monroe County District Attorney Sandra Doorley said in a news conference Wednesday.

In a July Facebook post, Doorley said she was devastated and outraged by the death of Officer Mazurkiewicz.

"Almost eight years ago, we lost a Rochester police officer in the line of duty," Doorley said. "After Officer Pierson's death, we said, never again. We came together as a community. We rallied and supported our police officers. Now, the violence in our city and hatred for police has claimed another one of the brave officers doing his best to protect our community."

Mayor Malik Evans said Wednesday, "This is not only a nightmare for them, the Mazurkiewicz family, but it's also a nightmare for our city, but the way we drive out darkness is to bring in more light, and the way to bring light is by making sure that we have justice."

"I am convinced that justice will be done in this case," he said.

Vickers will be arraigned later Wednesday or Thursday, Doorley said.

His official charges are:

  1. Aggravated murder for killing Officer Mazurkiewicz
  2. Murder in the 2nd degree for killing Officer Mazurkiewicz
  3. Attempt to commit the crime of aggravated murder for shooting Officer Seng
  4. Attempt to commit the crime of murder in the 2nd degree for shooting Officer Seng
  5. Assault in the 2nd degree for causing injury to Officer Seng with a deadly weapon
  6. Another count of assault in the 2nd degree for causing physical injury to a female victim with a deadly weapon
  7. Criminal possession of a weapon in the 2nd degree with the intent to use it unlawfully against another
  8. Criminal possession of a weapon in the 2nd degree for possession not in the defendant's home or place of business

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CNN's Zenebou Sylla contributed to this story.