At least three persons were killed and 100 injured in a commuter train derailment near Milan on Thursday.Firefighters were trying to free several people trapped in one carriage, between the stations of Treviglio and Pioltello, the Daily Star reported citing Italian media.A fire brigade official confirming the toll said he train, which was full of commuters, came off the tracks in the suburbs of Milan around 7 a.m.Ten people were critically injured. The cause of the crash was not yet clear.