BERLIN (AP) — Officials are investigating why part of a bridge in eastern Germany collapsed early Wednesday, disrupting a major traffic artery in Dresden and interrupting 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 shortly after 3 a.m. and are concerned more of the bridge — one of the city's four crossings over the Elbe — could collapse in the coming hours.

German news agency dpa reported that the last tram crossed the span just 18 minutes before the collapse.

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, and pipes that are part of the city's heating system were damaged as well.

“In addition, due to the bursting of two large district heating pipes, we have the problem that the supply of hot water has come to a complete standstill in the entire federal state capital of Dresden,” fire department spokesman Michael Klahre told reporters at the scene.

Dresden is about 160 kilometers (100 miles) south of Berlin.