LOS ANGELES (CNN) -- Officials have ruled the death of a 10-year-old girl who got into a fight last week to be a homicide, authorities said Monday.
Joanna Ramos, a fifth-grade student at Willard Elementary School, died of blunt force trauma to the head six hours after an altercation with a female classmate that lasted less than a minute, said Long Beach Police spokesman Sgt. Rico Fernandez.
Authorities have identified the other girl, who is 11, as well as several onlookers, and they are continuing to investigate what happened.
"There are several accounts of what transpired based on interviews with witnesses, but we have not concluded the precise motive," Fernandez said.
In a statement, police said Ramos and her unidentified classmate had challenged each other to a planned fight when their school session ended Friday. "The two girls met in a nearby alley next to a church and began hitting each other," Fernandez said.
The fight was brief, and no weapons were involved, authorities said.
According to Long Beach Unified School District spokesman Chris Eftychiou, Ramos finished her regular school session just after 2:10 Friday and was supposed to remain on campus to begin her scheduled after-school program at 2:30.
"We believe the altercation occurred during that 15-minute window because she apparently left and returned for the session, which involves help with homework and academic-related activity," said Eftychiou.
After the fight, the girls left and went their separate ways.
Ramos stayed in the afternoon session for about an hour but did not exhibit obvious signs of physical trauma, said Eftychiou. "When she did complain of not feeling well, her cousin picked her up, but we had no indication she was involved in an altercation," he said.
"Only when she was at the hospital did we get word about the altercation, and there is no indication that bullying was a factor," said Eftychiou.
Once the investigation and autopsy are complete, the findings will be turned over to the Los Angeles County District Attorney's Office for review and to determine whether charges will be filed in the case.
No arrests have been made, authorities said.
On Monday, grief counselors were brought into Willard Elementary to assist instructors and students. "It was a somber day," said Eftychiou.
Ramos had been enrolled at the school for about a year and a half, he said.