Venezuelan opposition leaders are fearing a crackdown and increased repression following a weird, alleged assassination attempt against the country's strongman president, Nicolas Maduro on Saturday night in Caracas.
Santos, who is due to hand over power to the hardline right-winger and vocal Maduro critic Ivan Duque on Tuesday, had said this week that the Venezuelan "regime has to fall" and that he could "see it happening in the near future".
Plotters flew one of the bomb-laden devices over the presidential stage with the goal of activating it near Maduro, but the area was equipped with devices that block invasive radio signals, Reverol said.
The president was giving a speech live on TV next to his wife, Cilia Flores, when he stopped and looked up to the sky after hearing an explosion. Seven NationalGuard soldiers were injured, Rodriguez added.
A second suspect had been detained during a wave of anti-Maduro protests in 2014 but had been released through "procedural benefits", Reverol said, without offering details. "It was so strong the building shook", she said "I said, 'Oh my God, what happened.' It terrified me".
"Justice! Maximum punishment! And there will be no forgiveness".
Venezuelan Interior Minister Nestor Luis Reverol said more arrests could follow in the incident, which he called a terrorist attack, according to the AP.
Venezuela's defense minister, Vladimir Padrino Lopez, said attackers were trying to take out the government's entire top leadership along with Maduro.
Correspondents say Maduro has relied heavily on the armed forces to keep power in the midst of an economic crisis and political turmoil.
Maduro accused neighboring Colombia and unidentified "financiers" in the United States of being behind the blast, while some of his officials blamed Venezuela's opposition.More news: Griffith Observatory to Host Mars Close Approach Viewing
The Colombian government has denied any involvement, saying there is "no basis" to Mr Maduro's allegations.
Colombia also rejected Maduro's "absurd" accusation of involvement.
USA national security advisor John Bolton insisted there was "no United States government involvement" and even suggested that the incident may have been "a pretext set up by the regime itself".
Earlier on Twitter, the group said it was made up of "patriotic military personnel and civilians loyal to the Venezuelan people who seek to rescue the democracy of a nation under dictatorship".
This year he brought forward to May presidential elections - boycotted by the opposition - which handed him a new six-year term.
However, Hasler Iglesias, a youth leader with the opposition Voluntad Popular Party, told the BBC: "It's hard to believe that the opposition is going to make an attempt when they have never made an attempt in this way in 20 years".
Late on Saturday, a civilian and military rebel group calling itself the "National Movement of Soldiers in T-shirts" claimed responsibility in a statement passed to US-based opposition journalist Patricia Poleo, who read it on her YouTube channel.
Reuters was unable to independently confirm the involvement of the group, which did not respond to requests for comment on the arrest announcements, or identify any of its members.
To add fuel to the confusion, local firefighters spoke anonymously to the AP, disputing the government's accounting.