A Toronto factory worker sorting through used clothing discovered a Second World War-era hand grenade inside a pillowcase early Tuesday, prompting a building evacuation and the temporary closure of area streets.

"I saw it. I said 'Get everyone out of here,'" said Omnitex owner, Imtiaz Somani. "Thank God it didn't go off."

The pineapple-shaped grenade was found at the used clothing reseller's factory at 120 The East Mall shortly after 9 a.m. ET.

Somani said employees were let off work as bomb squad officers were sent in to inspect the device and take it away.

Toronto police say they believe it was an isolated incident, and are investigating how it ended up at the factory.

Det. Steve Pattison said he believes it came from a donation box somewhere in the GTA.

The grenade is the second Second World War artifact to turn up in the Greater Toronto Area in the past week.

Several teenage boys found operational torpedoes in a half-buried box at an abandoned barn in Vaughan, north of the city, while playing near their house.