"Provincial officials including the governor, the police chief and other officials were accompanying the foreign guests to the plane when the gunshots happened", said Said Jan Khakrezwal, the head of the provincial council, according to Reuters.
The attack comes a day after a parliamentarian candidate and another key anti-Taliban figure from the Helmand province was killed in his campaign office.
NATO Resolute Support spokesman Grant Neely told RFE/RL that the top USA commander in Afghanistan, General Scott Miller, was present at the meeting but was unhurt.
Raziq and intelligence chief Abdul Mohmin died immediately in the attack and provincial governor Zalmay Wesa died of his injuries at a hospital.
Officials said Razeq, Miller and the other officials were walking toward a landing zone as the helicopter taking the USA general's party back to Kabul approached to land when the gunman, who was waiting outside, opened fire on the group. "Initial reports also say the attacker is dead", said Col. Knut Peters, a Resolute Support mission spokesman, in an email to NPR. "We are being told the area is secure".
An anti-Taliban commander was killed in a shooting in the southern Afghan city of Kandahar on Thursday in an attack involving the United States' top general in Afghanistan, sources said.
"Such brutal acts of the terrorists and their supporters can not weaken people's trust in the peaceful and democratic processes", President Ashraf Ghani said in a statement condemning the attack. A spokesperson for the provincial governor Omar Zwak said that "explosives were placed inside his [Qahraman's] sofa", reported Tolo News.
There were conflicting reports about the fate of governor Zalmai Wesa, with several lawmakers saying all three men had been killed.
Afghan policemen stand guard at a checkpoint ahead of parliamentary election in Kandahar on October 18, 2018.
More than 2,500 candidates are competing for 249 seats in the lower house of parliament.
The security meeting inside the sprawling provincial governor's residence was being held ahead of Saturday's parliamentary elections.
The election process has already been marred by bloody violence, with hundreds killed or wounded in recent months.
Earlier Wednesday, a parliamentary candidate in southern Helmand province was killed when a bomb exploded while he was holding a meeting in the courtyard of his campaign headquarters in the provincial capital, Lashkar Gah.