DENVER — Police say they found no signs of mechanical issues with a school bus that crashed earlier this month at Denver International Airport, killing the driver and injuring 18 others.

The Denver Post reports ( ) the investigation is still ongoing because an autopsy report of the driver is pending.

Police spokesman Doug Schepman says investigators still need to interview her husband.

It’s still unclear why the Legacy High School bus crashed head-on Sept. 11 into a pillar along one of the airport’s access roads.

Information from: The Denver Post,