The deaths occurred on Monday, bringing the death toll since the eruption of anti-Maduro protests three weeks ago up to 24, officials said.
Two of the victims died in the city of Merida. At least one of them was a government supporter.
Public defender Tarek William Saab said several other people were seriously wounded on Monday and were “between life and death.”
Referring to the government supporter killed in Merida, Saab said he “was demonstrating peacefully when he apparently received a gunshot.” It was not clear who shot him.
The third victim was killed in the nearby town of Barinas, a source in the prosecutor’s office said, without explaining whether he had been an anti-Maduro protester or a pro-government activist.
But an opposition party, Justice First, said the man had been participating in an anti-Maduro protest and had been targeted by armed pro-government groups.
Large-scale protests were held against Maduro on Monday, when demonstrators blocked major roads in the country. While most of the demonstrations were peaceful, there were instances of violence, including the three deaths, too.