Venezuelan President Nicolás Maduro says the perpetrators of what he says was an assassination attempt against him will face "maximum punishment".
He was speaking at a military event in Caracas when the alleged attack, involving explosive drones, occurred.
He has blamed Colombia for the incident but provided no evidence. Colombia said the accusation was "baseless".
The government has also pointed the finger at the opposition, prompting fears of a new crackdown.
Many opposition leaders have already left the country citing government harassment and there are reported to be more than 200 political prisoners in the country's jails.
The incident happened when Mr Maduro was speaking at an event to mark the 81st anniversary of the national army.
A bang is heard and footage of his speech shows the president suddenly looking upwards and dozens of soldiers running away.
Two drones loaded with explosives went off near the president's stand, Communications Minister Jorge Rodriguez said.
Seven soldiers were injured, and several people were later arrested, the Venezuelan authorities said.
Later Mr Maduro said the incident had strengthened his resolve.
"I am fine, I am alive, and after this attack I'm more determined than ever to follow the path of the revolution," he said.
"Justice! Maximum punishment! And there will be no forgiveness."
Mr Maduro accused neighbouring Colombia and elements within the US of instigating "a right-wing plot" to kill him.
The Colombian government has denied any involvement, saying there is "no basis" to Mr Maduro's allegations.
US National Security Adviser John Bolton denied any US involvement in the incident, adding that it could be "a pretext set up by the regime itself".
Mr Rodriguez accused Venezuela's right-wing opposition of carrying out the attack.
"After losing the vote, they failed again," Mr Rodriguez said.
He was referring to May's presidential elections, where Mr Maduro was re-elected for another six-year term.
However, Hasler Inglesias, 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."
Meanwhile, a little-known group called Soldiers in T-shirts said on social media that it was behind the alleged attack.
The claim was not backed up by any evidence, and the group did not respond to media requests for comment.
To add further to the confusion, firefighters at the scene disputed the government's version of events, the Associated Press reports.
Speaking on condition of anonymity, three of them said the incident was actually a gas tank explosion inside an apartment, but did not provide further details, the news agency says.