The driver of a school bus that struck and killed an Indianapolis elementary school principal had left the driver's seat without putting on the parking brake, according to an Indianapolis police report made available Monday.

Buses were lined up outside Amy Beverland Elementary School when the accident happened on Jan. 27. Students had boarded the bus and the driver was prepared to drive away when she left her seat, according to the police report, which doesn't say why the driver got up.

The bus rolled forward and fatally struck Principal Susan Jordan, who witnesses say pushed several students out of harm's way. Two 10-year-olds were injured.

Police have said they are working under the premise it was an unfortunate accident. Police initially said the bus driver told firefighters she was not sure what caused the bus to accelerate. A woman answering a phone listed for the driver said "no comment" and hung up.

The Associated Press is not releasing the driver's name because she has not been charged with a crime. Police have said it will be up to the prosecutor's office to decide whether any charges will be filed.

Peg McLeish, a spokeswoman for the Marion County prosecutor's office, told The Indianapolis Star that the case is still under investigation.

School officials have said the bus driver has no history of moving violations or discipline issues and described her as a model employee. Police said it likely would take weeks to get toxicology results back.

The police report was available on the website www.buycrash.com . Indianapolis Metropolitan Police Lt. Richard Riddle said Monday that the department wasn't releasing the report, but it had been forwarded to state police, which makes the information available to the website.