This was possible with gunpowder of that era, as for black powder, the chemical constituents are more or less the same as today's black powder used in hunting. The only real difference is that modern powder has certain stabilizers as it is "corned" into grains of specific size. The first gunpowder had a tendency to separate into charcoal, potassium nitrate, and sulfur. The grained, modern powders will not. As you can guess, re-mixing these chemicals was inconvenient and dangerous.

Early black powder had plenty of explosive force, and could have sent debris as far as claimed, but you would need a very big amount of it.

Studies of the 1605 Gunpowder Plot, where Guy Fawkes and his henchmen planned to blow up Parliament, killing King James I and the Parliament in session, have been made. The 36 barrels of powder in the Parliament building basement would have been enough to kill anyone within about a radius of 40 meters. Fawkes had a little over 2000 kilograms of powder.

A warehouse full would be a lot stronger. You need to keep in mind that black powder was used in 1566 to blow up the fortress of Szigetvár in Hungary when the Turks captured it. 3000 Turks were killed at the end of the siege by a booby trap of gunpowder in the castle's basement.