At least four elephants were killed and two others injured in Assam after a train hit a herd trying to cross railway tracks, officials said.The incident took place late Saturday night, P.J. Sharma, Chief Public Relations Officer of the Northeast Frontier Railway (NFR), said on Sunday.The elephants were killed near Hawaipur railway station when the Guwahati-Silchar passenger express train hit the herd, killing four of them on spot.Locals have claimed that the accident spot was an identified elephant corridor.They alleged that they tried to signal the loco pilot to slow down due to the movement of elephants.