Drones loaded with explosives detonated close to the event, Venezuelan Information Minister Jorge Rodriguez said, describing it as an "attack" against the leftist leader.
Mr Maduro was speaking in the capital Caracas on Saturday during a celebration of the National Guard's 81st anniversary when two blasts were heard at 5.40pm (10.40pm BST). The camera then cuts to the scene on the street, where soldiers and others in the crowd are seen running away from what may have been an explosion. There is no official word yet as to what occurred.
Seconds later Maduro and his wife, Cilia Flores, looked up to the sky and winced after apparently hearing an unidentified sound.
Elster tweeted, "Unconfirmed reports say it was an assassination attempt of Maduro by a drone, unclear if there is any casualties in this incident".
However, seven members of the Venzuelan national guard were injured and are being treated, Mr Rodriguez said.
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The country's economic turmoil compares to Germany's after World War I and Zimbabwe's at the beginning of the last decade, International Monetary Fund officials said, adding that Venezuela's economic contraction ranks among the world's deepest in six decades.
Smoke was later seen rising above the area where the explosion took place, as well as fire at a nearby building.
The soldiers lined up in ranks then begin running.
Mr. Maduro, who has governed a country suffering from hyperinflation, hunger and rampant violence, is deeply unpopular, polls show.