This paper develops an algorithm that guides a multi-robot system in an unknown environment searching for targets. The targets can be either fixed or moving. In order to locate all fixed targets and intercept all moving targets, the algorithm covers the entire free space in a sweeping fashion. No cellular decomposition of the area is performed. Communication between the robots is restricted. Two robots sense each other up to a maximum inter-robot distance, if their line-of-sight is not obstructed. A restricted number of robots are equipped with GPS; no broadcasting capabilities are assumed. The area to be scanned contains an unknown number of disjoint convex obstacles of unknown size and shape. The geometry of the robot group is a lateral line formation, which is allowed to split and rejoin when passing obstacles. Applications of the algorithm are mine field clearance, search-and-rescue missions, and intercept missions. Simulations are included and made available on the internet, demonstrating the flexibility of the algorithm.