The integration of several 2D laser rangefinders in a vehicle is a common resource employed for 3D mapping, obstacle detection and navigation. The extrinsic calibration between such sensors (i.e. finding their relative poses) is required to exploit effectively the sensor measurements and to perform data fusion. The approaches found in the literature to obtain such calibration rely either on the approximated parameters from the rig construction or on ad-hoc solutions to perform supervised data association in controlled conditions. In this paper we present a novel solution for the extrinsic calibration of a set of at least three laser scanners from the information provided by the sensor measurements. This method only requires the lasers to observe a common planar surface from different orientations, thus there is no need of any specific calibration pattern. This calibration technique can be used with almost any geometric sensor configuration (except for sensors scanning parallel planes), and constitutes a versatile solution that is accurate, fast and easy to apply. This approach is validated with both simulated and real data.