NASHVILLE, Tenn. (WKRN) — The shooter who took the lives of six people at The Covenant School last week fired a total of 152 rounds before being shot by officers, Nashville police said in an update on their investigation Monday.

According to police, Audrey Hale fired 126 rifle rounds and 26 nine-millimeter rounds while at the school. Based on the currently available information, investigators believe Hale worked alone.

Police also said collective writings written by Hale (found in the shooter’s bedroom and vehicle) show Hale was planning over a period of months to commit mass murder at The Covenant School. Hale also considered “the actions of other mass murderers,” the documents show.

Police said the writings remain under careful review by the Metro Nashville Police Department and the FBI’s Behavioral Analysis Unit in Virginia.

Two Metro police officers shot and killed Hale. Officer Rex Englebert shot a total of four rounds from his rifle, while officer Michael Collazo fired four rounds from his nine-millimeter pistol, police said.

Newly obtained search warrants released Monday revealed what investigators seized from the home of Hale.

Officers reported finding two shotguns, one in a bedroom closet and another next to a desk in a bedroom. Investigators also took 30 journals, some with references to school shootings and firearms courses.

A suicide note was also found, as well as five Covenant School yearbooks.

Investigators still have not determined a motive for the shooting. That part of the investigation remains ongoing by the homicide unit in consultation with the FBI’s Behavioral Analysis Unit.

As the investigation continues, the community mourns the six people killed in last week’s school shooting in Nashville with funerals and memorial services.

The children killed were Evelyn Dieckhaus, Hallie Scruggs and William Kinney. Also killed were Katherine Koonce, 60, the head of the school; Mike Hill, 61, a custodian, and Cynthia Peak, 61, a substitute teacher.

The Associated Press contributed to this report.