He said the drone fell to the ground and exploded, igniting a fire in an apartment. Crime scene investigators combed the building for evidence.
Venezuelan state television images showed Maduro looking up disconcertedly in the middle of a speech Saturday when a bang was heard, then uniformed members of the country's National Guard lined up in the parade suddenly breaking ranks and scattering.
"It was so strong the building shook", she said.
Once back in the presidential palace, Maduro said he had "no doubt" that Colombia's Santos - a Nobel Peace Prize victor who negotiated a historic peace accord with Marxist guerrillas FARC - was "behind the attack".
The attack highlights Maduro's challenges in maintaining control over the Opec nation, where widespread food and medicine shortages have fueled outrage and despair everywhere from hillside slums to military barracks.
Venezuela's government routinely accuses opposition activists of plotting to attack and overthrow Maduro, a deeply unpopular leader who was recently elected to a new term in office in a vote decried by dozens of nations.
Maduro later gave a separate address, stating: "A flying object exploded near me, a big explosion".More news: Call of Duty: Black Ops 4 - Multiplayer Beta Trailer
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Apparently in response, Bolton said, "If the government of Venezuela has hard information that they want to present to us that would show a potential violation of USA criminal law, we'll take a serious look at it". "Colombian President Juan Manuel Santos is behind this attack".
The parade Maduro attended was to mark the one-year anniversary of the Constitutional Assembly, a legislative body packed with Maduro loyalists that arrogated powers from the opposition-ruled National Assembly.
A clandestine group of Venezuelan soldiers claimed responsibility for Saturday's alleged attack against Maduro, in a statement obtained by el Nuevo Herald. The authenticity of the message could not be independently verified, and the organization did not respond to a message from the AP. "We didn't have success today, but it's just a question of time", said the group, which says it was founded in 2014 to bring together all of Venezuela's "groups of resistance".
One of the suspects had an outstanding arrest warrant for involvement in a 2017 attack on a military base that killed two people, Reverol said, an incident that followed four months of anti-government protests.
The arrests suggest the attack was less a military uprising than an assault led by groups linked to anti-Maduro street protesters, dubbed "The Resistance", who have led two waves of violent demonstrations that left hundreds dead.
In the midst of near-daily protests a year ago, a rogue police officer flew a stolen helicopter over the capital and launched grenades at several government buildings.
Germany said merely that it was "closely following developments on the ground", while Portugal opined that the crisis in Venezuela could be overcome by "dialogue and national consensus" in line with "democratic principles".