Police tightened security around the National Bureau of Investigation (NBI) office in Manila after finding firearms and a grenade inside a mysterious sport-utility vehicle (SUV) parked there Tuesday night. It was not clear if the development was related to the Nov. 23 Maguindanao massacre in which the main suspect in the case, Datu Unsay town Mayor Andal Ampatuan Jr., is detained at NBI headquarters. Government security forces have also tightened security in Metro Manila to prevent a spillover of the clan war that triggered the Nov. 23 massacre. A search of the vehicle yielded an M-16 rifle, a shotgun and a grenade. A record check showed the vehicle was registered in the name Cesar Detera of Quezon City. Manila Police District Mobile Division head Superintendent Ferdinand Quirante said they will invite Detera for questioning. He said the white Mitsubishi Pajero (EMS-333) was found at the corner of Padre Faura and Leon Guinto Streets in Manila at 10 P.M. Tuesday. On the other hand, security at the NBI was also tightened early Wednesday, with firearm-wielding NBI sentries standing guard at the bureau's Taft Avenue entrance. Police described the Pajero as “dirty,” with mud and earth inside the vehicle when a police team opened it to recover the firearms. The sighting of the vehicle caused tension among residents in the area, the report added.