A protester self-immolates outside the Israeli Consulate in Atlanta.

A protester self-immolated on Friday afternoon outside of the Israeli Consulate building in Atlanta, in what the police described as “likely an extreme act of political protest.”

A security guard tried to intervene but was unsuccessful, officials said. The demonstrator sustained third-degree burns to the body, and the guard was burned on his wrist and leg. Both were taken to Grady Memorial Hospital, where the protester was in critical condition.

Officials did not identify the demonstrator, but said in a news conference on Friday that the person appeared to be acting alone and that a Palestinian flag was “recovered at the location and was part of the protest.” The fire chief, Roderick M. Smith, said there was evidence of gasoline being used as an accelerant.

The city’s police chief, Darin Schierbaum, said that officials did not believe there was “any nexus to terrorism.” The building, in the Midtown area of Atlanta, houses the consulate and several other offices.

“It appears to have been focused outside the building. I’m not aware of an attempt to enter the building,” Chief Schierbaum said, adding: “I have met with the consul general. The staff is safe. All the residents of this building are safe.”

The Atlanta F.B.I. said it was aware of the incident and coordinating with local law enforcement. Chief Schierbaum said he was not aware of any credible threats against the building.

“It is tragic to see the hate and incitement toward Israel expressed in such a horrific way,” Anat Sultan-Dadon, consul general of Israel to the Southeastern United States, said in a statement on Friday. “The sanctity of life is our highest value. Our prayers are with the security officer who was injured while trying to prevent this tragic act.”