New Delhi, Oct 10: President A P J Abdul Kalam today expressed serious concern over the rape of a college girl by four soldiers of the presidential guards here on Monday and said tough measures should be taken to ensure that such incidents do not recur. "The President has expressed serious concern over the incident and called for tough measures to be taken to ensure that such incidents do not recur," a Rashtrapati Bhavan spokesman said. The spokesman said it was a serious matter and these men have committed a major offence and action should be taken against all the four. Bureau Report