(CNN) -- An explosion went off Friday at the office of a neo-Nazi group in Athens, Greek police said.

The daily newspaper Eleftherotypia received an anonymous phone call about the explosion 25 minutes beforehand, so the building was evacuated in time and no one was hurt, police said.

It happened at 8:50 a.m. (2:50 a.m. ET) at the fifth-floor office of Chryssi Avghi, a well known group whose name means "golden dawn." It was not known whether the group has been targeted before.

Police said the explosion was not large and that firefighters put out the resulting fire.