HELSINKI -- One person was killed and another seriously injured when a car bomb exploded at a busy intersection near Helsinki's railway station early Tuesday, police said.

The motive for the bombing, which killed the driver of the car, was not known, but police have not ruled out it being a revenge attack, spokesman Paivi Kaasinen, adding that the man, aged in his 30s, was known to them.

The bomb apparently went off when the car stopped at a traffic light, and also seriously injured the driver of a nearby car, AFP reported.

The blast occurred two blocks away from a synagogue that earlier this year received a bomb threat, but police said there were no links and ruled out any terrorist or political motives.