11:30 a.m.: Dyer said police believe Carrizales may have intended to induce Perry to take his life in a so-called "suicide by cop".
Dyer said Fresno police had had two prior contacts with Carrizales. In February 2005, Carrizales was found to be in possession of a butcher knife, Dyer said. Then, last Aug. 8, Carrizales' parents summoned police regarding their son. Dyer said he was precluded from discussing what prompted that contact.
Dyer said a small knife was found at the scene. Police are trying to determine if it belonged to Carrizales.
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11:20 a.m.: Fresno police chief Jerry Dyer today said the school resource officer who shot and killed a student at Roosevelt High School may have averted a greater tragedy at the school that could have occurred had the student grabbed the officer's gun.
At a news conference, Dyer detailed Wednesday's assault and said the officer was attacked from behind for no apparent reason. The officer, Junus Perry, was knocked to the ground and lost both his radio and his primary handgun.
The suspect continued to advance toward Perry with a bat over his head, yelling profanities at Perry and telling him, "What are you going to do now?" Dyer said.
Dyer said Perry yelled for help and drew a backup firearm from ankle holster and fired one shot at the student, hitting him in the chest.
The suspect fell backward, Dyer said. While the student was on ground, he yelled "Go ahead, kill me," Dyer said.
Arriving officers performed CPR on the student, Jesse Carrizales, but he died at the scene.
10:12 a.m.: Fresno police and Fresno Unified School District officials are planning a joint news conference this morning at the City Hall Annex in downtown Fresno to give the latest developments in Wednesday's incident at Roosevelt High School.
Visit fresnobee.com for live video from the conference beginning at 11 a.m.
On Wednesday a student was shot and killed by a Fresno police officer after he was attacked by the student with a baseball bat, according to police.
Police Chief Jerry Dyer and Ruthie Quinto, acting FUSD superintendent, will head the conference, which is scheduled for 11 a.m.
You will be able to watch the video here when the conference begins.