Officials are investigating why part of a bridge in eastern Germany collapsed early Wednesday, disrupting a major traffic artery in Dresden and impacting the city's heating system.

No one was injured when a section of the Carola Bridge fell into the Elbe River, the Dresden fire department said on its website. Emergency crews were alerted to the collapse shortly after 3 am.

Motorists, pedestrians and cyclists who use the bridge to go between the city's Old Town and New Town were told to avoid the area. Boat traffic is also halted, affecting cargo ships and tourism sightseeing vessels. A tram runs along the section of the bridge that collapsed.

Dresden is about 160 kilometres south of Berlin.