a propane explosoin flattened an industrial warehouse in Wisconsin's biggest city. Name the city

Question

Since this is not my area of expertise, I searched Google under the key words "propane explosion Wisconsin" to get this information:

Propane leak likely source of explosion - 12/08/2006 03:01 AM CST
BY EMILY FREDRIX and TODD RICHMOND, Associated Press
Investigators are looking at a propane leak as the cause of Wednesday's explosion that leveled a warehouse near downtown Milwaukee, Police Chief Nan Hegerty confirmed Thursday.

I hope this helps. Thanks for asking.