As many as 40 people were tied up for two hours Friday as a gang robbed Halifax's Costco store.

Four or five thieves wearing masks and black clothing stormed into the store's warehouse in the Bayers Lake Business Park just after 4. a.m. They were carrying guns.

The robbers tied up the few employees who were in the building, then bound other workers as they arrived.

The thieves left around 6 a.m. About a half-hour later, one person wriggled free and called 911.

"The employees ... are quite shaken up," says Const. Mark Hobeck, with Halifax Regional Police. "It was a very traumatic experience for them."

No one was injured. Hobeck says counsellors are on the way to help workers cope with their ordeal.

The thieves made off with a large quantity of cigarettes, and investigators are trying to determine if anything else is missing.

Hobeck says it's surprising that this type of robbery happened in Halifax. "It's not something we see very often ... We're taking it very seriously and we're doing what we can to get as much information and get on this as quickly as possible."

The store is closed while investigators search for clues

The store is closed while police search for clues

Investigators are looking for a cube U-haul van with Arizona licence plates, with a purple octopus or squid on the side.

The store remains closed while police gather evidence.

Costco employees did not want to comment. Officials from the store's head office in Ottawa are expected to arrive in Halifax Friday afternoon.