Armed men stormed the party headquarters of Venezuela opposition leader Juan Guaido on Friday, one day ahead of a protest against President Nicolas Maduro, Guaido and witnesses said.
Dressed in black and carrying pistols and rifles, the hooded men forced their way into the offices of Guaido's Voluntad Popular party in the east of the capital Caracas.
The men, who did not identify themselves, took security cameras and recording along with computers, money and identification from the approximately 30 people present.
"They were victims of a kidnapping, of intimidation," Guaido, who is recognized as Venezuela's acting president by about fifty countries, told journalists after arriving at the site minutes after the men left.
In a video broadcast by the party on Twitter, a man is heard yelling "everyone on the floor" and asking for the cellphones of the people in the office.
"It's enough that the dictatorship continues to intimidate our people, so we are going to the streets tomorrow with force throughout Venezuela," said Guaido, who had called the Saturday protest to demand that Maduro leave power.
Opposition politicians and founder of Voluntad Popular Leopoldo Lopez blamed "the coward Maduro" on Twitter for the incident.
"When are you going to understand that they are NOT going to break us?" he wrote, calling on citizens to turn "this outrage into action" in the streets.
On Twitter, the diplomatic representation in Venezuela of the United States -- which has rallied the international effort against Maduro -- tweeted that "we hold Maduro responsible for the safety of" Guaido.
Maduro's government called on their own supporters to mobilize on Saturday, and Maduro has warned the opposition that it will not allow a "coup d'etat" similar to the ouster of his Bolivian ally Evo Morales to happen in Venezuela.