"Our thoughts and condolences go out to the families and friends affected by this devastating, wicked, and barbaric act of domestic terrorism, leading to loss of precious lives,” Boakai's Unity Party said in a statement Tuesday.
“We urge the authorities to conduct a thorough and transparent investigation to determine the cause and hold those responsible accountable,” it added.
Authorities say the driver of a jeep without license plates switched off the lights of the vehicle and willfully struck a gathering of Unity Party supporters who were celebrating the final results of the November 14 runoff presidential election.
According to the National Elections Commission, Boakai won with 50.64% of the second round balloting while incumbent President George Weah took 49.36%.
Weah had already conceded defeat several days earlier based on the release of provisional results and urged his supporters to respect the vote's outcome.
The incumbent government on Tuesday extended its sympathies to the families of the victims. But in a news release urged the public "to refrain from making unsubstantiated claims about the incident, which has the potential of stoking post-elections violence.”
“The government takes particular note of a Unity Party statement, which appears to have drawn a conclusion, by terming the incident as domestic terrorism while at the same time urging the police to investigate the cause of the incident," the news release said.