Minneapolis (AP) — A maintenance worker at a Minneapolis school that partially collapsed after an explosion earlier this month had smelled natural gas and used a radio to tell others to evacuate less than a minute before the blast, according to preliminary report released Monday by the National Transportation Safety Board.

Two longtime school employees died in the Aug. 2 collapse at Minnehaha Academy.

The preliminary report doesn't identify the maintenance worker who urged people to evacuate, but the school identified him as Don DuBois, a Minnehaha Academy alum.

The NTSB report said DuBois hea...