Condoling the death of 23 people in the railway accident in Uttar Pradesh, West Bengal Chief Minister Mamata Banerjee on Saturday said safety should be the number one priority of the Indian Railways."Deaths due to accidents pain us all.Condolences to families who lost loved ones. Safety must always be No.1 priority of IndianR," Banerjee, a former Railway Minister, posted on her Twitter handle.At least 23 people were killed and 40 injured when 14 coaches of the Kalinga Utkal Express bound for Haridwar in Uttarakhand went off the tracks with one of the coaches mounting on another near Khatauli in Uttar Pradesh on Saturday evening.