At least two people have been wounded after shots were fired at a motorcade carrying Haiti's former president Jean-Bertrand Aristide.
Yvon Feuille, a senior executive of the Fanmi Lavalas political movement founded by Mr Aristide decades ago, described the shooting at a busy junction in central Port-au-Prince as an "assassination attempt".
Mr Feuille, who was in the motorcade with Mr Aristide surrounded by chanting Lavalas supporters, said the shooters were dressed as police officers.
Haitian National Police spokesman Garry Desrosiers said he did not immediately have any information about the attack or the claims being made about the shooters.
Mr Aristide's US lawyer Ira Kurzban said the shots were apparently "fired by uniformed police directly at the vehicle in which President Aristide was a passenger".
At least two people standing in front of the car were hit, he said.
"Thank God no-one was killed and at least one of the shooting victims was taken to the university medical centre that President Aristide was instrumental in founding," Mr Kurzban said from Florida.
Aristide lawyer Mario Joseph said the man taken to hospital was a security guard hired to protect the former president.
The Lavalas party circulated a photograph showing some blood on a car's front bumper and headlight.
The incident occurred after Mr Aristide appeared as a witness in a court hearing involving an associate who is facing a money laundering probe.
Although he has not been in power for nearly 13 years, Mr Aristide remains a highly divisive figure in Haiti, extremely popular with some and deeply reviled by others.
He emerged as a leading voice for Haiti's poor and became the troubled country's first democratically elected president in 1990, despite opposition from the army, Haiti's elite and the United States following the 29-year Duvalier family dictatorship.
Mr Aristide was toppled twice from power, his second term ending in 2004 amid a violent rebellion and allegations of corruption. He spent seven years in exile in South Africa.
The former Roman Catholic priest insisted he would not get involved in politics upon his return to Haiti in 2011, but he actively campaigned for Maryse Narcisse, the Lavalas presidential candidate who finished fourth in a presidential election re-run in November.
Before the campaign, he had mostly kept a low profile since returning. He was under house arrest in 2014 amid an investigation into corruption under his government.