A hostage kidnapped during a Northern California bank robbery was killed by police in an ensuing chase and shootout, likely during a final gunbattle where the lone surviving suspect used her as a human shield, authorities said Monday.

The results of a preliminary ballistics report show that police in the city of Stockton fired the 10 bullets that struck Misty Holt-Singh, 41, and all her wounds likely came during a final burst of gunfire, Stockton Police Chief Eric Jones said at a news conference.

Three men robbed a bank July 16, taking hostage Holt-Singh, a customer whose 12-year-old daughter was waiting in the car, and two bank employees, police said. Officers gave chase when the robbers, armed with three handguns and an AK-47, fled with the women in an SUV owned by one of the employees. They survived by either jumping or getting thrown from the SUV as it sped through town.

"We wanted, but never had the opportunity for, hostage negotiations," Jones said.

Jones said 33 officers fired at the vehicle, most of them during the final shootout. Officers were under constant fire and were concerned the suspects would kidnap other hostages, take over businesses or even a school.

"We believe July 16, 2014, brought dynamics never before seen in law enforcement," he said, adding that the suspects attempted to kill officers, fired more than 100 bullets and had about 200 rounds remaining when the gunfire ended.

Holt-Singh's family released a statement through their attorney, Greg Bentley, saying the ballistic information saddened them.

"The manner in which Misty's life was taken raises serious questions and concerns. The family is hopeful, however, that the promised information, policies, and procedures concerning the events of July 16 will be provided so that a fair, complete, and transparent investigation can take place."

Bentley has filed public-records requests for 911 calls, photographs, video and any other evidence documenting the incident, as well as law enforcement protocols for kidnappings, pursuits and the use of deadly force. Bentley has said he wants to know whether police made mistakes or suffered a communication breakdown.

Two of the suspects, identified as Alex Gregory Martinez, 27, and Gilbert Renteria Jr., 30, and Holt-Singh were found dead at the end of the final gunbattle. Jaime Ramos, 19, the sole surviving suspect, has been charged with murder.

Police previously said Ramos used Holt-Singh as a human shield, but they could not immediately tell whether she died from policegunfire or shots fired by the suspects.

They also did not know when she was killed.

While the full investigation will take more time, Jones said, he felt a need to release the preliminary information as soon as possible amid questions from the woman's family and the community. He disclosed the results of the preliminary ballistics report to Holt-Singh's family over the weekend.

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Investigators say they have linked Martinez to a robbery on Jan. 31 at the same bank branch through surveillance video, witness statements and comparable circumstances. Police said Monday they believe the suspects' AK-47 was used in other shootings.

Police were also continuing to try to identify the driver of a dark Buick sedan seen on video dropping off the suspects at the bank. The car, which has since been recovered, had no license plates and was abandoned in a neighborhood about a 10-minute drive from the bank.