The cause of a massive fire that destroyed two popular Yorkville restaurants last year has been classified as "undetermined."

Sotto Sotto and Spuntini Ristorante & Bar were burned down on Dec. 25, 2014. Investigators previously said the fire caused more than $1 million in damage.

On Wednesday, the Ontario Fire Marshal's Office told CTV Toronto investigators have completed their probe into the fire, and the cause of the blaze has been classified as "undetermined."

Sotto Sotto was considered a hotspot for many celebrities. Some of the restaurant's most famous clientele included Canadian hip-hop singer Drake, and actors Johnny Depp and Bruce Willis.

The restaurant's owner, Marisa Rocco, previously said she plans on rebuilding the Yorkville institution.

"We owe it to our history, our team and our loyal patrons to rebuild and we will come back stronger than ever," she said.