Four coaches of a passenger train were gutted in a fire in Bihar's Mokama railway yard on Wednesday, an official said. No one was injured in the incident.The coaches were of a MEMU (Mainline Electric Multiple Unit) passenger train that caught fire around midnight.At the time of the incident the train was stationed at the yard, around 80 km from Patna."The train had arrived in Mokama at 10.28 p.m. The fire was spotted in two of its coaches at 1.15 a.m. Soon the fire spread to two other coaches," a Railway Ministry official in Delhi said."The remaining 12 coaches of the train were saved as they were separated by the railway staff," the official said.The fire brigade from Barh, 30 km away from the spot, reached and completely doused the flames by 3.30 a.m.There has been no disruption though on the Patna-Howrah route due to the incident.An inquiry has been ordered to ascertain the cause of fire," the official added.