Aiyana Stanley-Jones Update: Grandmother testifies she watched Detroit cop shoot girl, 7

(CBS/AP) DETROIT - A Detroit grandmother testified Monday that she could only watch in terror as masked police officers with guns drawn stormed her home in a hunt for a murder suspect that led to the fatal shooting of Aiyana Stanley-Jones, her 7-year-old granddaughter.

PICTURES: Aiyana Jones, 7, Killed by Cop

Police officer Joseph Weekley is charged with involuntary manslaughter in the May 2010 death of Aiyana, who was asleep on a couch when police raided the house. Aiyana's grandmother, Mertilla Jones, said she was lying on her stomach on the floor facing the door when the police officers forced their way inside.

"As soon as they came in, their guns were just pointing right there, and he pulled the trigger," Mertilla Jones said of Weekley. "I seen the light leave out of her eyes and the blood started gushing out her mouth and she was dead."

There is no argument that an unintentional shot from Weekley's gun killed Aiyana after police fired a stun grenade and stormed the home. Weekley has said his gun accidentally fired when Jones reached for it. Prosecutors say he was negligent in failing to control his weapon.

Jones said there were only seconds between the police entering the house and the shot being fired. She said Aiyana's head was propped against the armrest of the couch as she slept and that Weekley was holding the gun right next to the armrest when his weapon discharged.

"The gun went off and shot her in the head. I started screaming and hollering. ... `Y'all done killed my grandbaby,"' Jones told the courtroom.

Jones said she didn't interfere with or touch any of the officers, who were dressed entirely in black, including their masks and combat boots. Police were accompanied by a crew from the reality TV show, "The First 48."

Last week, a neighbor testified that he tried to tell officers before they raided the home that children were inside. Under cross-examination Monday, Jones said the officers were negligent.

"They knew there were children in there. So why would they come in there like that? They came to kill, and they killed a 7-year-old."

Complete coverage of Aiyana Stanley-Jones on Crimesider