Rights groups say 11 people have died in Venezuelan unrest. Authorities say they have arrested more than 1,000 protesters

At least 11 people have been killed in protests that have engulfed Venezuela since the July 28 presidential election, according to the NGO Foro Penal, as reported by CNN. The country's authorities, in turn, report that 77 police officers have been injured in clashes with protesters. More than 1,000 people have been detained.

Nicolás Maduro, who declared himself the winner of the election, called the protesters criminals and said their actions were being coordinated from the United States. Venezuelan Defense Minister Vladimir Padrino López called the protests an attempted coup and said the army expressed "absolute loyalty and unconditional support" to the Maduro regime.

Opposition party Voluntad Popular said its leader Freddy Superlano had been kidnapped. Shops closed and public transport stopped operating in Venezuela on July 31, Reuters reports .

Nicolás Maduro has been in power since 2013, and was running for the third time. According to the Electoral Council of Venezuela, he received 51% of the vote, while opposition candidate Edmundo González allegedly received 44%. The opposition, however, claims that according to its calculations based on observers, González actually received twice as many votes as Maduro.