The more than 600 rounds that Stockton, Calif., police fired during a rolling gun battle with bank robbers last year that left a hostage dead by officers' bullets was "excessive" and "unnecessary," according to the Police Foundation, a research group based in Washington, D.C.

The report released Monday detailed how Stockton police responded to the July 16, 2014, armed robbery of a Bank of the West branch, where three gunmen took three women hostage and fired at officers from a speeding SUV, reports the Los Angeles Times .

The group found that 32 officers unloaded more than 600 rounds during the hour-long rolling gun battle, which spanned three counties, 63 miles of highway and reached speeds of 120 mph. One of the hostages, Misty Holt-Singh, was killed when she was struck by 10 police bullets, authorities said. The two other hostages jumped or were thrown from the vehicle during the chase and survived.

Police officials said they fired on the vehicle to potentially save lives because the men in the car were shooting indiscriminately. The gunmen disabled 14 police cars with gunshots, the report stated.

Since the incident, Holt-Singh's family has sued the department, and the surviving gunman has been charged with murder.