CNN  —  Armed and hooded members of the Venezuelan security forces have surrounded Argentina’s embassy in Caracas, according to leaders of the country’s opposition. Six members of the opposition are currently taking refuge in the embassy, having fled there to escape a crackdown by Venezuelan authorities in the run-up to July’s presidential elections. Pedro Urruchurtu, who has been in the embassy since March and is the international coordinator for opposition leader Maria Corina Machado , wrote