The Federal Bureau of Investigation and Mexican authorities are investigating who started a fire outside the U.S. consulate in Tijuana that destroyed four cars, a U.S. official said on Friday.

The official said that another vehicle was partially damaged. There were no reported injuries. Local media reported the fire took place early Friday morning.

The U.S. consulate in Tijuana, located across the border from San Diego, is one of the busiest in Mexico. A U.S. consulate worker in the border city of Juarez was killed by drug gang gunmen in 2010.