Toronto police say that a fourth suspicious package has been discovered at a costume store in Etobicoke, Ont., hours after the store reopened.

Explosive packages were found at Amazing Party and Costume Store amid the Halloween rush over the weekend, and police said they received another call regarding the store shortly after 7 p.m. on Monday.

Police have called in the bomb squad again, and have evacuated the store.

On Friday, a bomb squad was called to the business, which is located near the Gardiner Expressway and Islington Avenue, after staff found a suspicious package.

Two more packages were found at the location over the weekend. A bomb disposal robot was used to remove them from the scene.

Police confirmed the initial packages contained explosives, although they would not say what kind of explosives were inside.

The closure came at an inopportune time for the party store, as the weekend before Halloween is typically the busiest time of year for costume shopping.

The Amazing Party and Costume Store confirmed the incident on a posting on their website and promised they would return to regular business hours on Monday.

"There are no words to express the gratitude we feel towards our loyal customers, suppliers and neighbours for their support and understanding during this act of terrorism," read the posting.

Everything in the store was to be sold at a 50 per cent discount.