"In close cooperation with the respective authorities, all staff have been evacuated as a matter of precaution. At present, police experts are on site to conduct investigations," said a Mercedes spokesperson to Reuters.
According to Hungarian news website Index, bomb-sniffing dogs are at the factory and the general area is on lockdown.
The Kecskemét plant builds some of Mercedes' compact, front-wheel drive models, including the CLA-Class and B-Class. According to official figures, the plant employed 3,358 people as of the end of 2013 and built 109,266 vehicles that year.
Autoblog has contacted Mercedes for more details. We'll add more information as it becomes available.