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Off-duty Forest County sheriff's deputy Tyler James Peterson, 20, killed six young people at a post-homecoming pizza party in Crandon, Wisconsin, on Oct. 7, 2007, then shot himself and died after a standoff, authorities said.

Peterson, a full-time Forest County sheriff's deputy who also worked part time for the Crandon police, forced his way into the home about 2:45 a.m. and opened fire with an AR-15 rifle, authorities said.

The dead, all current or former Crandon High School students, were Jordanne Murray, 18, whom Peterson had dated for about four years; Aaron Smith, 20; Bradley Schultz, 20; Katrina McCorkle, 17; Lianna Thomas, 17; and Lindsey Stahl, 14. Charlie Neitzel, 21, survived after being shot three times and lying still as if dead.

The 911 recordings released by investigators days later began with Crandon patrolman Greg Carter's frantic call after he arrived at the duplex. "He is shooting to kill," Carter told a dispatcher, according to the tapes. One neighbor reported hearing two bursts of gunfire and watching a man run to a pickup truck and drive off.

Dispatchers told callers in the town of about 2,000 to stay inside and lock their doors. "Right now it would probably be best if you just locked all your doors," one dispatcher said.

Peterson fired on Carter's squad car as he fled, drove to a friend's home near Argonne, about seven miles north, and acknowledged what he had done, investigators said. A friend eventually called 911 to report where he was. After a standoff, a police sniper wounded Peterson in the arm, and Peterson shot himself and died. Investigators said the attack followed an argument between Peterson and Murray, who had recently ended their relationship.