A railway Officials said the train smashed the crowded bus, which was carrying a groom's family and friends back from a wedding, bdnews24 reported.
The train 'Simanta Express' was going to Khulna from Syedpur and was passing the crossing around 3.45 a.m., the official said.
The bus carrying the bridal party drove on to the unmanned railway crossing without checking for a train.
"The train ploughed through the bus and dragged it more than a kilometre along the tracks," the official said.
Local people, fire service and police began a rescue operation at the crash site and retrieved the bodies, including children and women.
The injured were rushed to nearby hospitals.