Spain's worst terrorist attack was in March 2004 when 191 people were killed by bombs planted by Islamists on commuter trains in Madrid.
Britons in the Catalan capital described running for their lives after a suspected Islamist terrorist drove a van into crowds through the central tourist hot spot of Las Ramblas.
"Global Affairs Canada is communicating with local authorities in order to gather additional information and we are in contact with the family members of the affected Canadian citizens in order to provide consular assistance". More than 100 were also injured.
The victims - both deceased and wounded - were from at least 34 different countries, including France, Germany, China, Australia and Peru, Spanish emergency services announced Friday.
The minute of silence was held near where the driver of the van started the attack.
"A woman injured yesterday in #Cambrils attack has died".
In Cambrils, police shot dead five people wearing fake bomb belts who plowed into a group of tourists and residents with a vehicle.
Meanwhile, an Italian foreign ministry official says two Italians are among those confirmed dead in the Barcelona attack.
Where the Las Ramblas attack utilised a van, the Cambrils one utilised an Audi A3, which was flipped with its back window smashed following the attack.
The Spanish Prime Minister called the attack "jihadi terrorism".
Moussa Oukabir, said to be a Spanish national of Moroccan heritage, had previously written about "killing infidels" in a chilling online post and has not been seen since the first attack took place. "Be tough & strong, we love you!"
There is so far no word on whether anyone from Britain was injured or killed.