Three shots were fired Tuesday at buses in the campaign convoy of former Brazilian leader Luiz Inacio Lula da Silva, who is again running for the presidency.
The incident occurred as the convoy was traveling between towns in southern Brazil as part of a campaign tour for Lula, who is trying to make a comeback in the October 7 presidential election.
"Our convoy is being targeted by fascist groups," Lula wrote on Twitter.
"They have already thrown eggs, stones. Today they fired a shot at a bus," he said.
Workers Party leader Gleisi Hoffmann told AFP by telephone that two shots hit a bus carrying reporters and a third shot hit a different vehicle.
Hoffmann said she and Lula were traveling in the only bus that was not hit.
The party leader also said they were attempting to determine if Lula was the target of an assassination attempt.
The alleged shooting came two days after Lula and his entourage were pelted with eggs and stones while on a campaign stop. An angry Lula wrote on his website at the time that "vandals, fascists" were to blame.
Although still widely popular in Brazil, the 72-year-old Lula is campaigning under a dark legal cloud that could yet scupper his attempt to return to power.
On Monday, a Brazilian court rejected his appeal against a corruption conviction that could see him imprisoned for 12 years and disqualified from holding public office.
The ex-president remains free while the Supreme Court considers his argument that he should not be imprisoned until he has exhausted all of his appeal options. The court said it would rule on that on April 4.