SACRAMENTO, Calif. >> A rookie Sacramento police officer was shot during a domestic violence call and lay wounded for about 45 minutes as the gunman kept officers at bay with bursts of fire, authorities said today. She was finally rescued with an armored vehicle but died at a hospital.

“We are devastated,” Deputy Chief Dave Peletta said. “There are no words to convey the depth of sadness we feel or how heartbroken we are for the family of our young, brave officer.”

Officer Tara O’Sullivan, 26, was shot Wednesday evening while helping a woman collect her belongings to leave her home. As officers swarmed the area, the gunman continued firing in a standoff that lasted about eight hours before he surrendered.

Stephen Nasta, a professor at the John Jay College of Criminal Justice and a former inspector with the New York Police Department, said taking 45 minutes to reach a wounded officer is “unacceptable.”

If officers couldn’t immediately get an armored police vehicle to the scene, he said, they should have commandeered an armored bank vehicle, bus or heavy construction equipment.

“If there’s somebody shot, lying on the ground, you have to do everything you can,” Nasta said.

If no such vehicle was available, he said he would expect police to use a diversionary tactic such as firing at the home, setting off smoke grenades or breaking a door or window in another part of the home to distract the gunman as other officers rescued the wounded comrade.

O’Sullivan graduated from the police academy in December and was working with a training officer. She was expected to be on her own in a couple of weeks, Peletta said.

She and other officers arrived at the home at 5:41 p.m. A half-hour later the first shots were fired, and O’Sullivan was hit, authorities said. The gunman continued firing a rifle-type weapon. At 6:54 p.m., additional officers responded with an armored vehicle to rescue O’Sullivan.

“Our officers maintained cover in safe positions until we were able to get an armored vehicle in the area,” Sgt. Vance Chandler said.

Five minutes later, O’Sullivan was taken to UC Davis Medical Center, where she died.

The woman she was helping was not hurt, and the relationship between that woman and the gunman was not immediately known. Police gave no immediate details on the gunman.

O’Sullivan grew up in the San Francisco Bay Area and graduated last year from Sacramento State University with a degree in child development.

Mayor Darrell Steinberg said on Facebook that O’Sullivan was in the first graduating class of a groundbreaking program at Sacramento State that “emphasizes the importance of inclusion and cultural competence for future law enforcement leaders — of which Tara undoubtedly would have been.”