The Central Bureau of Investigation conducted a raid on the Delhi government's forest department ofices on Monday and seized documents in connection with a fraud pertaining to the purchase of tree guards. Sources said CBI officials raided the forest department headquarters at Kamla Nehru ridge, south division office at the Tughlakabad shooting range, the office at Anand Vihar nursery, Alipur city forest office, the office of the Deputy conservator of forests (west) apart from other place in the city.