A Halloween search warrant resulted in officers seizing 250 firearms, 200,000 rounds of ammunition and a grenade, Waterloo Regional Police Service says.

Officers with the drugs and firearm unit conducted an investigation that involved searching a home on Strathcona Crescent in Kitchener.

"It was to our surprise [that] we were given information that a number of firearms were seen in plain view," said Const. Ashley Dietrich.

Police examined the grenade and determined it was real but was not live, Dietrich said.

A 57-year-old Kitchener man has been charged with unsafe storage.

Dietrich said more firearms-related charges against another man are anticipated.

No injuries were sustained during the execution of the search warrant.

Police are still investigating to determine why there were so many guns in the house, Dietrich said.