The family of a Hofstra University student who was killed during a hostage incident last May is suing the officer who fired the fatal shot, the department that employed him, and Nassau County, N.Y.

Andrea Rebello, 21, was killed when Officer Nikolas Budimlic of the Nassau County Police Department fired upon a man who had taken her hostage in an off-campus apartment. The hostage taker, Dalton Smith, 30, was also killed. Smith had convictions for robbery and was wanted for a parole violation.

The wrongful death lawsuit claims the officer "carelessly discharged" his firearm during the incident, the Associated Press reports. The suit also accuses the department of negligence and says Budimlic acted "recklessly and unnecessarily" when he fired eight shots at Smith who was using Rebello as a shield.

"We believe that if the police had not come to the house that night, our daughter would still be alive," the Rebello family told Newsday through their Manhattan attorney David Roth.

The lawsuit accuses the police department of failing to properly train officers and communications operators on how to handle hostage situations, and of inadequate supervision during such incidents.

According to the suit, the county and police are also negligent for a history of finding that "every police-involved shooting was justified" and never disciplining officers who are involved in deadly shootings.

The District Attorney has ruled the shooting justified.

Police Benevolent Association president James Carver told Newsday the gunman who held the students hostage is the only one to blame for Andrea Rebello's death.

Related: 

Police Union Defends N.Y. Officer In Rebello Shooting

N.Y. Cop 'Torn Up' Over Hostage's Death