Venezuelan authorities have arrested six people they call "terrorists and hired killers" in what President Nicloas Maduro says was an assassination attempt against him.

The apparent attack during a a military parade Saturday involved two explosives-laden drones. One is said to have blown up in midair before reaching its target and the other smashed into an apartment building and later blew up.

Interior Minister Nestor Reverol says "important information" was collected during the raids in Caracas that resulted in the six arrests. He gave no other details.

Television pictures showed Maduro making a speech about the Venezuelan economy when an explosion was heard. Maduro glanced up and first lady Cilia Flores looked skyward, frightened with her hand to her chest.

The soldiers that had been standing in formation for the parade scattered.

Another blast took place at a building near where Maduro was speaking. A resident of the building told VOA Venezuelan correspondent Adriana Nunez that a drone fell into an adjacent parking lot and exploded.

An unharmed Maduro appeared on television hours later, saying "everything points" to a right-wing plot he claims originated in neighboring Colombia -- a charge the Colombian government says is "without foundation.

He added that an initial investigation shows people living in the U.S. state of Florida financed the plot.

"I hope that President Donald Trump is ready to fight these terrorist groups," Maduro said, accusing the United States of imperialism and trying to stir up a civil war in Venezuela.

U.S. National Security Advisor John Bolton told Fox television Sunday "unequivocally there was no U.S. government involvement in this at all." (VOA)

•Venezuelan President Nicolas Maduro reacts during an event that was interrupted, reportedly by explosives from drones, in this still frame taken from government video, Aug. 4, 2018, in Caracas, Venezuela.