A passenger train derailed in central Greece, injuring 23 people, railway officials said.

The train had been traveling from Athens to the northern city of Thessaloniki when it derailed about 270 miles north of the capital near the city of Larissa overnight, Greek railway company OSE said.

Twenty adults and three children were taken to a nearby hospital. Most were treated and released, but 11 injured remained in the hospital by early afternoon for observation, OSE said. It did not specify whether the three children were among the 11.

OSE said it was not clear what caused the derailment, and the company has launched an investigation.