TOPEKA (AP) – The Kansas state fire marshal’s office is waiting for debris from a deadly explosion at a grain elevator to be cleared as investigators look for the cause.

Six people, including two grain inspectors, were killed in Saturday night’s blast at the Bartlett Grain Co. elevator in Atchison, about 50 miles northwest of Kansas City.

Chief Special Agent Rose Rozmiarek said Wednesday the fire marshal’s office hopes to have a preliminary report on the explosion next week.

Rozmiarek said parts of the elevator remain inaccessible because of the debris.

The elevator is still smoldering at the top, and Rozmiarek said that because of the grain inside, it’s likely to continue to smolder for some time.