Meanwhile, hundreds more pro-independence supporters protested outside a courthouse in the north-eastern Catalan town of Hospitalet de Llobregat to demand the release of the arrested officials.
The leader of Catalonia's regional government, Carles Puigdemont, said on Thursday his administration would push on with a banned October 1 referendum on a split from Spain, in defiance of a court order banning the vote.
Spain's Interior Ministry says it's deploying police reinforcements to its northeastern region of Catalonia to maintain order and take action if a referendum on independence pledged by the Catalan government but deemed illegal by Spain should take place. "We are respecting the Spanish Constitutional order", said the Berlaymont spokesperson, adding that no phone call is on the European Commission President Jean-Claude Juncker's plans at the moment. Police said up to 40,000 people gathered outside the devolved government's economy ministry in the city, which was searched.
Many who do not support independence say they are scared to speak out and no longer feel comfortable in their own country.
Sturgeon, who is the leader of the pro-independence Scottish National Party (SNP), on Thursday backed the Catalan regional government for planning the referendum, saying that "the right of self-determination is an important worldwide principle".
The central government in Madrid has blocked the vote and chartered three ferries in the ports of Barcelona and Tarragona to house additional police dispatched to the region.
Mr Puigdemont had accused the central government of effectively suspending devolution after it moved to seize control of regional finances to stop them being used to fund the referendum.
Also on Friday, a Catalan regional judge ordered the release with restrictions of six people arrested on Wednesday in a crackdown on referendum preparations.
Spain's central government says the planned October 1 referendum is illegal.