Six people have been arrested, accused of "terrorism" and attempting to assassinate Venezuela President Nicolas Maduro with explosive-laden drones.
"We believe that the regime will launch a fierce attack against the opposition, there will be more violations of human rights, and this gives rise to arrest, accuse and persecute the opposition within the country", said José Antonio Colina, president of Venezolanos Perseguidos Políticos en el Exilio (Veppex).
He said seven soldiers had been injured, with three of them in a critical state.
Reverol said one of the detained had an outstanding arrest warrant for his alleged role in the August 2017 attack on a military base in Valencia. "We have identified the people who made the explosives and prepared the weapons and their worldwide links", Saab said.
"I have no doubt that everything points to the right, the Venezuelan ultra-right", Maduro said on Saturday night.
No drones could be seen in the television broadcast, which showed bodyguards jumping in front of Maduro to protect him with flexible ballistic shields.
"It could be a lot of things from a pretext set up by the Maduro regime itself to something else", United States national security adviser John Bolton told conservative news network Fox on Sunday.
"I hope the Trump administration is willing to fight terrorist groups that commit attacks in peaceful countries in our continent, in this case Venezuela".
He also blamed Venezuelans living in the United States.
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Colombia's Foreign Ministry in response said it "emphatically rejected" Maduro's accusations. One was "diverted" by security forces while the second fell on its own and hit an apartment building, Reverol said.
There are now fears that, whatever was behind the event, the Venezuelan government will use it to justify further crack downs on the opposition and to silence any dissenting voices.
Here's what happened. Per the Associated Press, at around 5:30pm ET, Maduro took the stage at a celebration of the National Guard's 81st anniversary.
Santos, meanwhile, tweeted directly to Maduro, saying, "Don't worry".
The attack came as Venezuela is reeling from an economic and humanitarian crisis and Maduro has grown increasingly isolated. The drones, according to officials, were flown towards Maduro as he addressed soldiers in Caracas on Saturday.
Maduro's security team led him to safety.
Last year, a rogue Venezuelan police officer hijacked a helicopter and fired at government buildings in what he said was an action against a dictator. Maduro, a former bus driver, won a new six-year term in May but his main rivals disavowed the election and alleged massive irregularities.