MONTREAL — Armed police officers converged Friday on the Montreal offices of Ubisoft, a French video game company, in response to a 911 call, and dozens of people were evacuated, but no threat was found and no injuries were reported.

During the police operation, local television reports showed Ubisoft staff on the roof of their office building with doors barricaded. A police SWAT van was seen in the area.

The police did not immediately clarify the nature of the 911 call.

Gilles Douaire, an online programmer at Ubisoft, said the episode appeared to have been a prank, “like somebody confused Friday the 13th with April 1st.”

In a LinkedIn message, Mr. Douaire said employees evacuated to the roof and to meeting rooms in adjacent buildings because the police were “not taking any chances.” Ubisoft Montreal is a campus that occupies several buildings in the area, he said.

Ubisoft employees said they had received instructions from the authorities telling them to barricade themselves, to hide and to put their phones in silent mode.

The incident convulsed the surrounding neighborhood, called Mile End, which is well known for its bagel emporiums, a large Hasidic community and a cluster of high technology companies, of which Ubisoft is one of the major players.